Fixed GC issue.

yaml.encode() now wraps a string literal whose content is equal to a
null or a boolean value representation in YAML into single quotes. Those
literals are: 'false', 'no', 'true', 'yes', '~', 'null'.

Reverted the a2d7643c commit to use single quotes instead of multiline
encoding for 'true' and 'false' string literals.

Follows up #3476
Closes #3662
Closes #3583

Use lua_is*() functions instead of explicit lua_gettop() checks in
yaml.encode() and yaml.decode() functions.

Behaviour changes:

* yaml.decode(object, nil) ignores nil (it is consistent with encode
  behaviour).
* yaml.encode() gives an usage error instead of "unsupported Lua type
  'thread'".
* yaml.encode('', {}, {}) ignores 3rd argument (it is consistent with
  decode behaviour).

I. Fixes tarantoolctl rocks install hanging in resctricted networks
corner-case.

A customer configured two rocks servers:
1. offline (file:///path/to/rocks)
2. and default online (rocks.tarantool.org)

He tries to do `rocks install http 1.0.5-1`.

Online server is unavailable due to his local network policy, but
the rock is available offline. Despite anything, luarocks still
tries to fetch manifest online, which results in 30 sec hang since
network access is restricted.

This change aborts scanning when exact match is found

II. Remove cyclic dependencies

This is required to embed luarocks into tarantool, as
current tarantool preloader can't preload cyclic dependencies.
There should be a unidirectional dependency graph and
predictable order.

Note: as a consequence of this patch, operating systems other that
unix-compatible ones are no longer supported. This is because I
had to manually resolve dependency graph for predictable require()
order.

III. Use digest.md5_hex to compute md5 digests instead of openssl

luarocks has support for calculating md5 with 'md5' rock if it's
present, but we don't have it in tarantool, and instead have the
'digest' module. That's why luarocks falls back to 'openssl' binary
to calculate md5 digests.

This patch will allow luarocks to use our internal digests module.

Add an ability to pass options to json.encode()/decode().

Closes: #2888.

@TarantoolBot document
Title: json.encode() json.decode()
Add an ability to pass options to
json.encode() and json.decode().
These are the same options that
are used globally in json.cfg().

A possibility to build tarantool with included library dependencies.
Use the flag -DBUILD_STATIC=ON to build statically against curl, readline,
ncurses, icu and z.
Use the flag -DOPENSSL_USE_STATIC_LIBS=ON to build with static
openssl

Changes:
  * Add FindOpenSSL.cmake because some distributions do not support the use of
  openssl static libraries.
  * Find libssl before curl because of build dependency.
  * Catch all bundled libraries API and export then it in case of static
  build.
  * Rename crc32 internal functions to avoid a name clash with linked libraries.

Notes:
  * Bundled libyaml is not properly exported, use the system one.
  * Dockerfile to build static with docker is included

Fixes #3445

Strings containing "true" and "false" were converted
to a boolean type when serializing. Fixed.
Example:
type(yaml.decode(yaml.encode('false'))) == string
type(yaml.decode(yaml.encode('true'))) == string

Closes #3476.

New commit in third_party/libyaml downgrades
required cmake version.

Closes #3275.

Now it is possible to specify a number in exponential
form via all formats allowed by json standard.
json.decode('{"remained_amount":2.0e+3}')
json.decode('{"remained_amount":2.0E+3}')
json.decode('{"remained_amount":2e+3}')
json.decode('{"remained_amount":2E+3}')     <-- fixed

Closes #3514.

YAML formatting C API is needed for #2677, where it will be used
to send text pushes and prints as tagged YAML documents.

Push in the next patches is implemented as a virtual C method of
struct session, so it is necessary to be able format YAML from C.

Needed for #2677

Yaml.decode tag_only option allows to decode a single tag of a
YAML document. For #2677 it is needed to detect different push
types in text console: print pushes via console.print, and actual
pushes via box.session.push.

To distinguish them YAML tags will be used. A client console for
each message will try to find a tag. If a tag is absent, then the
message is a simple response to a request.

If a tag is !print!, then the document consists of a single
string, that must be printed. Such a document must be decoded to
get the printed string. So the calls sequence is
yaml.decode(tag_only) + yaml.decode. The reason why a print
message must be decoded is that a print() result on a server side
can be not well-formatted YAML, and must be encoded into it to be
correctly sent. For example, when I do on a server side something
like this:

console.print('very bad YAML string')

The result of a print() is not a YAML document, and to be sent it
must be encoded into YAML on a server side.

If a tag is !push!, then the document is sent via
box.session.push, and must not be decoded. It can be just printed
or ignored or something.

Needed for #2677

Encode_tagged is a workaround to be able to pass options to
yaml.encode().

Before the patch yaml.encode() in fact has this signature:
yaml.encode(...). So it was impossible to add any options to this
function - all of them would be treated as the parameters. But
documentation says: https://tarantool.io/en/doc/1.9/reference/reference_lua/yaml.html?highlight=yaml#lua-function.yaml.encode
that the function has this signature: yaml.encode(value).

I hope if anyone uses yaml.encode(), he does it according to the
documentation. And I can add the {tag_prefix, tag_handle} options
to yaml.encode() and remove yaml.encode_tagged() workaround.

Encode_tagged allows to define one global YAML tag for a
document. Tagged YAML documents are going to be used for
console text pushes to distinguish actual box.session.push() from
console.print(). The first will have tag !push, and the
second - !print.

OOM is not single possible error. Yaml library during dump can
raise such errors as YAML_MEMORY_ERROR, YAML_WRITER_ERROR,
YAML_EMITTER_ERROR. And each of them can contain any error
message that is skipped now, because Tarantool YAML does not
provide such API, that can lead to a non-OOM error.

But it is changed in next commits.

Any option of base64 leads to urlsafe encoding. It is wrong, and
caused by incorrect flag checking. Fix it.

Closes #3358

Closes #3148

EV_USE_REALTIME and EV_USE_MONOTONIC, which force libev to use
clock_gettime, are enabled automatically on Linux, but not on OS X. We
used to forcefully enable them for performance reasons, but this broke
compilation on certain OS X versions and so was disabled by commit
d36ba279 ("Fix gh-1777: clock_gettime detected but unavailable in
macos"). Today we need these features enabled not just because of
performance, but also to avoid crashes when time changes on the host -
see issue #2527 and commit a6c87bf9 ("Use ev_monotonic_now/time
instead of ev_now/time for timeouts"). Fortunately, we have this cmake
defined macro HAVE_CLOCKGETTIME_DECL, which is set if clock_gettime is
available. Let's enable EV_USE_REALTIME and EV_USE_MONOTONIC if this
macro is defined.

Closes #3299

* no-wrap: do not wrap each 72 result symbols on a new line;
* no-pad:  do not add padding at the end of a result;
* urlsafe: no-wrap + no-pad + replace '+' -> '-' and '/' -> '_'.

Closes #2777
Closes #2478
Closes #2479

Update zstd submodule to v1.3.1 version.

The fallthrough attribute with a null statement serves as a fallthrough
statement. It hints to the compiler that a statement that falls through
to another case label, or user-defined label in a switch statement is
intentional and thus the -Wimplicit-fallthrough warning must not trigger.
The fallthrough attribute may appear at most once in each attribute list,
and may not be mixed with other attributes. It can only be used in a switch
statement (the compiler will issue an error otherwise), after a preceding
statement and before a logically succeeding case label, or user-defined
label.

https://developers.redhat.com/blog/2017/03/10/wimplicit-fallthrough-in-gcc-7/

ev_now()/ev_time() are affected by system time changes, which makes them
impractical for calculating timeouts. Introduce ev_monotonic_now() and
ev_monotonic_time() which work exactly as ev_now()/ev_time(), but use
monotonic clock instead of realtime.

Needed for #2527

getopt_long() is available on all supported platforms.
Get rid of legacy gopt and use getopt_long().

Incompatible changes:

 * `tarantool --version --no-such-option` printed
    "unrecognized option '--no-such-option'", now it displays version.
    `tarantool --no-such-option --version` still prints an error message.

Needed for #1265

Do not use thumb specifier for asm code, use unified syntax directive
instead.

Closes #2609
Closes #2633
Closes #2616

Fix inaccurate patching by ed412cd9 commit in LuaJIT.

Remove libbfd from dependencies and use libunwind for stack traces.

Closes #2103

Usage:

    tarantoolctl rocks install ROCK - install a rock
    tarantoolctl rocks remove ROCK - remove a rock
    tarantoolctl rocks show ROCK - show information about an installed rock
    tarantoolctl rocks search PATTERN - search repository for rocks
    tarantoolctl rocks list - list all installed rocks

There are no other commands, options, configuration files. Our official
repository (http://rocks.tarantool.org) works out of the box. All rocks
are installed to ${PWD}/.rocks directory to support separate rocks trees
per project, as proposed by #2067. Rockspec can use "tarantool >= 1.7.x"
inside dependencies = {} block to depend on a specific Tarantool version.

LuaRocks has been slightly hacked to support custom configuration
via site_config.lua. There are no other changes in the upstream code.
It is not a fork and it isn't going to be a fork. All formats, layouts
and rockspecs are 100% compatible with the upstream LuaRocks 2017-07-10.

This feature intentionally doesn't have CMake option to disable it,
because it should be provided on all available platforms out of the box.

Other changes:

 * Add ${PWD}/.rocks to default package.path/package.cpath
 * Hack tarantoolctl to display subcommands in --help.
   Currently command line arguments handling are not perfect, but
   it can be fixed only by a new argparse implementation.

Closes #2067

Now open MP sort is used for any size of an array.
For small arrays it's an overkill and even can cause overhead
due to thread pool creation.

Invoke open MP sort only for big arrays and use old good
single-thread qsort for small arrays.

Fix #2431

No semantic changes.

Needed for #128

This code was added by me, it is not covered by lua-yaml
copyrights and can be moved to src/.

See cd0d6f25 "incorrect error handling in lyaml".

Needed for #128

* Inline IS_PRINTABLE macros into check_utf8()
* Rename yaml_check_utf8() to utf8_check()
* Get rid of libyaml-private dependency for lua-yaml

Needed for #128

Apply a patch from Yura Sokolov:

The default "fast" string hash function samples only a few positions in
a string, the remaining bytes don't affect the function's result. The
function performs well for short strings; however long strings can yield
extremely high collision rates.

An adaptive schema was implemented. Two hash functions are used
simultaneously. A bucket is picked based on the output of the fast hash
function. If an item is to be inserted in a collision chain longer than
a certain threshold, another bucket is picked based on the stronger hash
function. Since two hash functions are used simultaneously, insert
should consider two buckets. The second bucket is often NOT considered
thanks to the bloom filter. The filter is rebuilt during GC cycle.

Highlights from Mike Pall [1]:

The major addition over beta2 is the LJ_GC64 mode JIT compiler
backend contributed by Peter Cawley. Previously, only the x64 and
ARM64 interpreters could be built in this mode. This mode removes
the 32 bit limitation for garbage collected memory on 64 bit systems.

LuaJIT for x64 can optionally be built for LJ_GC64 mode by
enabling the -DLUAJIT_ENABLE_GC64 line in src/Makefile or via
'msvcbuild.bat gc64'.

Cisco Systems, Inc. and Linaro have sponsored the development of
the JIT compiler backend for ARM64. Contributors are Djordje
Kovacevic and Stefan Pejic from RT-RK, Charles Baylis from Linaro
and Zheng Xu from ARM. ARM64 big endian mode is now supported, too.

Cisco Systems, Inc. has sponsored the development of the MIPS64
interpreter and JIT compiler backend. Contributors are Djordje
Kovacevic and Stefan Pejic from RT-RK.

Peter Cawley has contributed the changes for full exception
interoperability on Windows/x86 (32 bit).

François Perrad has contributed various extensions from Lua 5.2 and
Lua 5.3. Note: some left-over compatibility defines for Lua 5.0
have been removed from the header files.

[1]: https://www.freelists.org/post/luajit/LuaJIT210beta3

In context of #2396