LuaJIT submodule is bumped to introduce the following changes:
* GC64: disable sysprof support
* build: make -DLUAJIT_DISABLE_SYSPROF work
* test: disable sysprof C API tests with backtrace
* tools: introduce parsers for sysprof
* sysprof: introduce Lua API
* memprof: add profile common section
* core: introduce lua and platform profiler
* memprof: move symtab to a separate module
* core: separate the profiling timer from lj_profile
* vm: save topframe info into global_State

Within this changeset a parser for binary data dumped via the sampling
profiler to Tarantool binary. It is a set of the following Lua modules:
* sysprof/parse.lua: decode the sampling profiler event stream
* sysprof/collapse.lua: collapse stacks obtained while profiling
* sysprof.lua: Lua script and module to display data

Besides, all new public Lua C API introduced within this changeset is
added to extra/exports.

Closes #781

NO_DOC=LuaJIT submodule bump
NO_TEST=LuaJIT submodule bump