Thread: rename check by cgeck_counter to avoid conflict with macro.
Thread: rename wait_until parameter to avoid shadow with member function.
Thread: link with boost_chrono and boost_atomic independently of the platform.
Started to extract synchronization primitives from Boost.Thread to Boost.Sync. Work in progress, not usable ATM.
Added shared_lock_guard. Removed make_lock_guard as it is not always reliable because it technically requires lock_guard to be copyable or moveable.
Thread: fix more typos in doc.
Thread: fix some typos in doc.
Thread: avoid conflict with thread symbol.
Thread: fix scoped_thread variadic constructor.
Thread: try to handle with call_once intel issue #8943.
Thread: try to handle with not needed definition of uintptr_t #8817.