Now QBasicMutex is Lockable and QMutex is TimedLockable, which means they can
be used in std::lock_guard, std::unique_lock, std::lock, etc.
[ChangeLog][QtCore][QMutex] QMutex now fully models the TimedLockable
concept by providing the try_lock, try_lock_for and try_lock_until
functions, therefore making it usable in Standard Library lock
management classes and functions.
Change-Id: I7c691481a5781a696701e1ab78186b5cefbd6a87
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>