libstdc++-v3/
	* include/std/atomic (compare_exchange_weak, compare_exchange_strong):
	Add call to __cmpexch_failure_order.
	* testsuite/util/testsuite_common_types.h
	(compare_exchange_order_lowering): New generator.
	* testsuite/29_atomics/atomic/requirements/compare_exchange_lowering.cc:
	New test.

From-SVN: r201315