Cleaned up the tests code according to the Lua style guide:
- made scoped variables local
- added os.exit call at the end of the test chunk
- adjusted the messages in test:ok calls

(cherry picked from commit 3c641629)

- Make string to number conversions fail on NUL char.

(cherry picked from commit 12694d72)

- gdb: adjust the extension to be used with Python 2
- gdb: introduce luajit-gdb extension

(cherry picked from commit a81453b9)

libcurl has a built-in threaded resolver used for asynchronous DNS
requests, however, when DNS server is slow to respond, the request still
hangs tarantool until it is finished. The reason is that curl calls
thread_join on the resolving thread internally upon timeout, making the
calling thread hang until resolution has ended.
Use c-ares as an asynchronous resolver instead to eliminate the problem.

Closes #4591

(cherry picked from commit 23837076)

Revert "build: introduce LUAJIT_ENABLE_PAIRSMM flag"

Related to #4770

(cherry picked from commit 04dd6f43)

When json.decode is used with 2 arguments, 2nd argument seeps out to the
json configuration of the instance. Moreover, due to current
serializer.cfg implementation it remains invisible while checking
settings using json.cfg table.

This fixes commit 6508ddb7 ('json: fix
stack-use-after-scope in json_decode()').

Closes #4761

(cherry picked from commit f54f4dc0)

Update decNumber library to silence the build warning produced on too
long integer constant.

(cherry picked from commit aab03a73)

Fix build on Mac with gcc and XCode 11

Part of https://github.com/tarantool/tarantool/issues/4580

List of changes
     - fold: keep type of emitted CONV in sync with its mode
     - test: adjust the test name related to PAIRSMM flag

(cherry picked from commit e12930d0)

Inside json_decode() struct luaL_serializer is allocated on stack, but
json context stores pointer to it:

   998	static int json_decode(lua_State *l)
   999	{
  ...
  1007	    if (lua_gettop(l) == 2) {
  1008	        struct luaL_serializer user_cfg = *luaL_checkserializer(l);
  1009	        luaL_serializer_parse_options(l, &user_cfg);
  1010	        lua_pop(l, 1);
  1011	        json.cfg = &user_cfg;
  1012      }

Later (for instance in json_decode_descend()), it can be dereferenced
which in turn results in stack-use-after-scope (object turns into
garbage right after scope is ended). To fix it let's simply avoid
allocating and copying luaL_serializer on stack and instead use pointer
to it.

Bug is found by ASAN: test app-tap/json.test.lua fails with enabled
ASAN. Current fix allows to pass all tests.

Thanks to @Korablev77 for the initial investigation.

Closes #4637

(cherry picked from commit 6508ddb7)

Add LUAJIT_ENABLE_PAIRSMM flag as a build option for luajit.
If the flag is set, pairs/ipairs metamethods are available in
Lua 5.1.
For Tarantool this option is enabled by default.

(cherry picked from commit 93e710d5de0d723086bda6fedc9cb383a8e5e477)

Wrap throwing lua_newthread in luaT_newthread using luaT_cpcall
to process arising error properly.

Closes #4556

(cherry picked from commit 54e23d6d)

(cherry picked from commit 8749b3e1)

Count lines in the json parsing structure. It is needed to print
the number of line and column where a mistake was made.

Closes #3316

(cherry picked from commit 9f9bd3eb2d064129ff6b1a764140ebef242d7ff7)
(cherry picked from commit 53d43160)

Closes #4434
Follow-up #4366

@TarantoolBot document
Title: json/msgpack.cfg.encode_deep_as_nil option

Tarantool has several so called serializers to convert data
between Lua and another format: YAML, JSON, msgpack.

YAML is a crazy serializer without depth restrictions. But for
JSON, msgpack, and msgpackffi a user could set encode_max_depth
option. That option led to crop of a table when it had too many
nested levels. Sometimes such behaviour is undesirable.

Now an error is raised instead of data corruption:

    t = nil
    for i = 1, 100 do t = {t} end
    msgpack.encode(t) -- Here an exception is thrown.

To disable it and return the old behaviour back here is a new
option:

    <serializer>.cfg({encode_deep_as_nil = true})

Option encode_deep_as_nil works for JSON, msgpack, and msgpackffi
modules, and is false by default. It means, that now if some
existing users have cropping, even intentional, they will get the
exception.

(cherry picked from commit d7a8942a)

The submodule was on 7.65.3 version. This update closes two security
problems:

https://curl.haxx.se/docs/CVE-2019-5482.html
https://curl.haxx.se/docs/CVE-2019-5481.html

See also curl-7.66.0 release notes:

https://curl.haxx.se/changes.html#7_66_0

Fixes #4502.

(cherry picked from commit 4c2d1eff)

If the rock was packed with luarocks then the time in it is set to zeros
and this is not the case with the unix format can be removed when date given
is added to zipwriter_open_new_file_in_zip (luarocks/luarocks#1056)

Closes #4481

(cherry picked from commit 3658cb00)

The json.encode() used to cause a segfault in case of recursive
table:
  tbl = {}
  tbl[1] = tbl
  json.encode(tbl)

Library doesn't test whether given object on Lua stack parsed
earlier, because it performs a lightweight in-depth traverse
of Lua stack. However it must stop when encode_max_depth is
reached (by design).

Tarantool's lua_cjson implementation has a bug introduced during
porting original library: it doesn't handle some corner cases:
entering into a map correctly increases a current depth, while
entering into an array didn't. This patch adopts author's
approach to check encode_max_depth limit. Thanks to handling this
constraint correctly the segfault no longer occurs.

Closes #4366

(cherry picked from commit d2641e66e65ab57317b8e70bb7115517ec81238e)

Hold libcurl-7.65.3. This version is not affected by the following
issues:

* #4180 ('httpc: redirects are broken with libcurl-7.30 and older');
* #4389 ('libcurl memory leak');
* #4397 ('HTTPS seem to be unstable').

After this patch libcurl will be statically linked when
ENABLE_BUNDLED_LIBCURL option is set. This option is set by default.

Closes #4318

@TarantoolBot document
Title: Tarantool dependency list was changed

* Added build dependencies: autoconf, automake, libtool, zlib-devel
  (zlib1g-dev on Debian).
* Added runtime dependencies: zlib (zlib1g on Debian).
* Removed build dependencies: libcurl-devel (libcurl4-openssl-dev on
  Debian).
* Removed runtime dependencies: curl.

The reason is that now we use compiled-in libcurl: so we don't depend on
a system libcurl, but inherit its dependencies.

(cherry picked from commit 7e51aebb)

(cherry picked from commit 03a39c3d)

(cherry picked from commit a634bd7d)

We will use it for Lua console output format serialization

Part-of #3834

Made tarantoolctl compatible with luarocks-3.x.

Fixes #4052.

Add fixed-point decimal type to tarantool core.
Adapt decNumber floating-point decimal library for the purpose, write a
small wrapper and add unit tests.

A new decimal type is an alias for decNumber numbers from the decNumber
library.
Arithmetic operations (+, -, *, /) and some mathematic functions
(ln, log10, exp, pow, sqrt) are available together with methods to
pack and unpack decimal to and from its packed representation (useful
for serialization).

We introduce a single context for all the arithmetic operations
on decimals, which enforces both number precision and scale to be
in range [0, 38]. NaNs and Infinities are restricted.

Part of #692

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.