Remove atomic_compare_and_exchange_bool_rel.

Remove atomic_compare_and_exchange_bool_rel.

atomic_compare_and_exchange_bool_rel and
catomic_compare_and_exchange_bool_rel are removed and replaced with the
new C11-like atomic_compare_exchange_weak_release.  The concurrent code
in nscd/cache.c has not been reviewed yet, so this patch does not add
detailed comments.

	* nscd/cache.c (cache_add): Use new C11-like atomic operation instead
	of atomic_compare_and_exchange_bool_rel.
	* nptl/pthread_mutex_unlock.c (__pthread_mutex_unlock_full): Likewise.
	* include/atomic.h (atomic_compare_and_exchange_bool_rel,
	catomic_compare_and_exchange_bool_rel): Remove.
	* sysdeps/aarch64/atomic-machine.h
	(atomic_compare_and_exchange_bool_rel): Likewise.
	* sysdeps/alpha/atomic-machine.h
	(atomic_compare_and_exchange_bool_rel): Likewise.
	* sysdeps/arm/atomic-machine.h
	(atomic_compare_and_exchange_bool_rel): Likewise.
	* sysdeps/mips/atomic-machine.h
	(atomic_compare_and_exchange_bool_rel): Likewise.
	* sysdeps/tile/atomic-machine.h
	(atomic_compare_and_exchange_bool_rel): Likewise.