`say_logrotate` does not rotate logs synchronously. It posts tasks to
coio which executes them in it's pool thread. On application exit we
destroy logs calling `log_destroy`. This function waits for rotate task
to finish because if it will free resources immediately then unfinished
rotate task can have use-after-free issues. Waiting crashes because at
this moment event loop is not running which is required for
`fiber_cond_wait` to work.

Note that if there is no crash then we will hang forever waiting in
`log_destroy` because event loop is not running and
`log_rotate_async_cb` will never be executed.

Let's use mutexes and conditions instead. It solves both problems with
crash and hang. Thanks Vladimir Davydov for idea.

Fixes #4450

NO_DOC=bugfix

(cherry picked from commit eed09192)

strerror() is MT-Unsafe, because it uses a static buffer under the hood.
We should use strerror_r() instead, which takes a user-provided buffer.
The problem is there are two implementations of strerror_r(): XSI and
GNU. The first one returns an error code and always writes the message
to the beginning of the buffer while the second one returns a pointer to
a location within the buffer where the message starts. Let's introduce a
macro HAVE_STRERROR_R_GNU set if the GNU version is available and define
tt_strerror() which writes the message to the static buffer, like
tt_cstr() or tt_sprintf().

Note, we have to export tt_strerror(), because it is used by Lua via
FFI. We also need to make it available in the module API header, because
the say_syserror() macro uses strerror() directly. In order to avoid
adding tt_strerror() to the module API, we introduce an internal helper
function _say_strerror(), which calls tt_strerror().

NO_DOC=bug fix
NO_TEST=code is covered by existing tests

(cherry picked from commit 44f46dc8)

There are a few tests that create files in the system tmp directory
and don't delete them. This is contemptible - tests shouldn't leave
any traced on the host. Fix those tests.

Closes #3688

* Remove rewriting format of default logger in case of syslog option.
* Add facility option parsing and use parsed results in format message
  according to RFC3164. Possible values and default value of syslog
  facility are taken from nginx (https://nginx.ru/en/docs/syslog.html)
* Move initialization of logger type and format fucntion before
  initialization of descriptor in log_XXX_init, so that we can test
  format function of syslog logger.

Closes gh-3244.

* Refactor tests.
* Add ev_async and fiber_cond for thread-safe log_rotate usage.

Follow up #3015

Under FreeBSD getline prototype is not provided by
default due to compatibility problems.
Get rid of getline (use fgets instead).
Based on @locker proposal.

Closes #3217.

Current log rotation is not async signal safe.
In order to make it so refactor signal handling
with ev_signal.

Log rotation for each logger performs in separate
coio_task to provide async and thread-safe execution.

Relates #3015

* Add check on NULL filename in format functions
* The need of this fix was inspired by possible need of custom loggers
which want to reuse our format functions

* Add struct log
* Add possibility to add logger configuration to global scope
* Refactor functions in say to use them with specified config,
 not only global variable

 This patch was inspired by need of additional logger in audit log
 Relates #2912

* Pull error processing from functions say_XXX_init(file, pipe, sys)
to say_log_init
* Remove error processing with passing point error
message as an argument
* Add new exception IllegalParameters

* Add log_format option to box.cfg{}
* Add json format in logging
* Add table converting to json in lua logging

Closes #2795

Create a different type of logger for boot mode.

In context of #2795

Improves usability of `log` Lua module for scripting.

Fixes #1876