* src/globals.cc: Define globals _GLIBCPP_mutex_init (),
	_GLIBCPP_mutex_address_init (), _GLIBCPP_once, _GLIBCPP_mutex
	and _GLIBCPP_mutex_address.
	* include/bits/stl_threads.h (_STL_mutex_lock): Use above to provide
	once-only runtime initialization of _M_lock mutex when
	__GTHREAD_MUTEX_INIT_FUNCTION is defined.
	(__STL_MUTEX_INITIALIZER): Provide initializer for _STL_mutex_lock
	for __GTHREAD_MUTEX_INIT_FUNCTION case.

From-SVN: r43360