* include/std/mutex (call_once): Remove parentheses to fix error in
	c++1y and gnu++1y mode.
	* testsuite/30_threads/mutex/try_lock/2.cc: Call try_lock() in new
	thread to avoid undefined behaviour.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@199875 138bc75d-0d04-0410-961f-82ee72b054a4
Daily bump.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@199878 138bc75d-0d04-0410-961f-82ee72b054a4