Thread: apply pathc for #8931.
Thread: Add mutex() to upgrade_to_unique_lock (#8891).
Thread: Added synchronized_value operator() to synchronize around a function call.
Thread: fix type and add BOOST_THREAD_USE_ATOMIC macro doc.
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.
Minor update - ported to BOOST_EXPLICIT_OPERATOR_BOOL.
Added a skeleton for docs with the notes for maintainers.
Fixed docs build.
Thread: protect condition_variable/_any wait_for and wait_until from malicious input.
Thread: protect condition_variable/_any wait_for and wait_until from malicious input.