libstdc++: Add mem_order_hle_acquire/release to atomic.h v2

libstdc++: Add mem_order_hle_acquire/release to atomic.h v2

The underlying compiler supports additional __ATOMIC_HLE_ACQUIRE/RELEASE
memmodel flags for TSX, but this was not exposed to the C++ wrapper.
Handle it there.

These are additional flags, so some of assert checks need to mask
off the flags before checking the memory model type.

libstdc++-v3/:
2013-01-12  Andi Kleen  <ak@linux.intel.com>
	    Jonathan Wakely  <jwakely.gcc@gmail.com>

        PR libstdc++/55223
	* include/bits/atomic_base.h (__memory_order_modifier): Add
	__memory_order_mask, __memory_order_modifier_mask,
	__memory_order_hle_acquire, __memory_order_hle_release.
	(operator|,operator&): Add.
	(__cmpexch_failure_order):  Rename to __cmpexch_failure_order2.
	(__cmpexch_failure_order): Add.
	(clear, store, load, compare_exchange_weak, compare_exchange_strong):
	Handle flags.
	* testsuite/29_atomics/atomic_flag/test_and_set/explicit-hle.cc:
	Add.

Co-Authored-By: Jonathan Wakely <jwakely.gcc@gmail.com>
From-SVN: r195321