Added -DENABLE_LTO=ON/OFF cmake option, OFF by default.

LTO speeds up cpu-intensive workloads by up to 20% (see [1] and [2]).

Requirements to enable LTO:

- cmake >= 3.9;
- Linux: ld.bfd / ld.gold from binutils >= 2.31 (or later 2.30)
  (gold >= 1.15);
- Mac OS: xcode >= 8 (earlier versions are not tested).

The requirement of the recent ld version is due to bug with exporting
symbols from dynamic list when LTO is enabled, see [3].

Note: -Wlto-type-mismatch on GCC (enabled by default with -flto) gives
namy warnings. Filed [4] to investigate it.

Note: LuaJIT will be compiled w/o LTO despite the option set, filed [5].

[1]: https://github.com/tarantool/tarantool/wiki/performance-research
[2]: https://gist.github.com/Khatskevich/31a2da6ab46ce903120e7a03d65966db
[3]: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84901
[4]: https://github.com/tarantool/tarantool/issues/3742
[5]: https://github.com/tarantool/tarantool/issues/3743

Closes #3117

f

Added MAKE_BUILD_TYPE=RelWithDebInfoWError option, which means enabling
-DNDEBUG=1, -O2 and -Wall -Wextra -Werror. This ensures we have clean
release build without warnings.

Fixed found -Wunused-variable and -Wunused-parameter warnings.

Part of #3238.

The problem is that clang does not support -Wno-cast-function-type flag.
It is the regression from 8c538963.

Follow up of #3685.
Fixes #3701.

Since addition of -fopenmp to compiler also means
addition of -lgomp to the link stage, pass -fno-openmp
to the linking stage in case of static build. In that
case OMP functions are statically linked into libmisc.

Also, emit error if trying to perform static build using
clang.

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

Fixing build under FreeBSD:
Undefined symbol "iconv_open"
Add compile time build check with FindICONV.cmake
and a wrapper to import relevant symbol names with include file.

Closes #3441

No more `include/yaml.h` and `lib/libyaml_static.a` installs.

closes gh-3547

If curl does not have SSL support, don't panic, honor CURL_FIND_REQUIRED
variable, and panic only if it's set.

Correct the grammar in the error message.

On MAC several old curl versions don't support SSL by default.
Try to check it and print error message if so.

Close #3065

Fast ucol_strcollUTF8 function was introduced in ICU 50. In older
ICU versions we have to use slower ucol_strcollIter with properly
initialized UTF8 iterators.

Fix #2820

The option is '-DENABLE_BUNDLED_ZSTD' and defaults to ON.

There are two goals of making this conditional, both related to building
Tarantool on Gentoo Linux from an ebuild:

* Avoid bundled ZStd building issue w/o pay to investivage it.
* Allow user to choose between system and bundled library.

Apple's version of libcurl is outdated and buggy.
Use libcurl from homebrew by default.

Closes #2772

Speed up zstd as much as possible.

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/

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

Add an option to enable LuaJIT's GC64 mode and enable this option
by default on OS X.

Closes #2643

LuaJIT has some configuration flags which can be switched via
-DLUAJIT_USE_OPTION defines, e.g. USE_ASAN or USE_VALGRIND.
Before this patch these definitions were added by CMake to XCFLAGS
variable and passed to LuaJIT's Makefile. However, some of these
flags also affect the content of lj_xxx.h internal header files,
which were included by Tarantool (see utils.c) and compiled WITHOUT
proper flags. This situation might lead to inconsistent ABI between
compiled libluajit.a and Tarantool.

This patch adds all LUAJIT_USE_XXX defines to CMake's COMPILE_FLAGS
in order to enable these flags globally, then parses COMPILE_FLAGS
and adds them to LuaJIT's XCFLAGS.

Needed for #2643

Add missing #include <trivia/config.h>

Fixes #2635

Remove libbfd from dependencies and use libunwind for stack traces.

Closes #2103

Now module.h is autogenerated automatically on `make all`
if one or more source header files have changed.

Closes #2481

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

In context of #2312
See #1906

* Supress warnings in third-party code.
* Fix false-positive "variable may be used uninitialized in this function"
* Add MAYBE_UNUSED to variables used only for assertions
* Fix compilation on GCC 6.3.0 20170205
* Fix compilation on GCC 7.0.1 20170316
* Fix compilation on Clang 5.0.0-svn294894-1

Add missing -isysroot flag for LuaJIT on macOS.

Fixes #2091

* Move platform-specific defines to tt_pthread.h
* Set sched.coro.stack only with ENABLE_ASAN

Please note that pthread_getattr_np() + pthread_attr_destroy()
combination is totaly broken on Glibc 2.12 (RHELL 6.x).

Fixes #2085

Sophia was an experimental storage engine in 1.6.x.
Please use 'vinyl' engine in Tarantool 1.7 instead.

Closes #2040

We don't need these functions anymore.

* Check for missing cpuid.h header
* Fix sed magic in extra/mkexports
* Fix open_memstream implementation
* Fix CLOCK_PROCESS_CPUTIME_ID / CLOCK_THREAD_CPUTIME_ID
* Disable stupid -Wchar-subscripts warnings
* Add a workaround for "undefined __gcc_personality_v0"

Tested on NetBSD 7 and on x86_64-rumprun-netbsd.
Now you can use Tarantool on toasters.

 * Fix cross-compilation of LuaJIT
 * Fix txt2c and bin2c for cross-compilation
 * Check for invalid CMAKE_SYSTEM_PROCESSOR values

libreadline needs termcap OR curses/ncurses.

* Add HAVE_PTHREAD_ATTR_GET_NP to detect pthread_attr_get_np
* Add relation from pthread_attr_get_np to pthread_getattr_np as define
* Support BSD sed for mkexports

Fixes #2010

This patch is not perfect, but it is better than nothing.

+ Remove third_party/valgrind and third_party/pmatomic which
  also exist in src/lib/small/third_party.