exports: add `tarantool_version`

The `tarantool_version` symbol identifies the binary as Tarantool (see also
https://github.com/tarantool/tarantool/blob/f991f7c0be73558f0710f0af871d07e8bd506efe/tools/tarabrt.sh#L179-L180

).
It is not exported and thus can be optimized away by LTO — add it to the
exports list.

Closes #8129

Acked-by: Aleksandr Lyapunov <alyapunov@tarantool.org>

NO_CHANGELOG=<internal change>
NO_DOC=<internal change>
NO_TEST=<no convenient way to test devtools>

extra/exports

@@ -469,6 +469,7 @@ swim_size
 tarantool_exit
 tarantool_lua_slab_cache
 tarantool_uptime
+tarantool_version
 title_get
 title_get_custom
 title_get_interpretor_name

static-build/test/exports.test.lua

@@ -76,6 +76,7 @@ local check_symbols = {
     'say_set_log_format',
     'tarantool_uptime',
     'tarantool_exit',
+    'tarantool_version',
     'log_pid',
     'space_by_id',
     'space_run_triggers',