Handle alignment in __atomic_is_lock_free

Handle alignment in __atomic_is_lock_free

gcc:

2015-09-17  Richard Henderson  <rth@redhat.com>

	PR libstdc++/65913
	* builtins.c (fold_builtin_atomic_always_lock_free): Handle fake
	pointers that encode the alignment of the object.

libstdc++-v3:

2015-09-17  Jonathan Wakely  <jwakely@redhat.com>

	PR libstdc++/65913
	* include/bits/atomic_base.h (__atomic_base<_TTp>::is_lock_free(),
	__atomic_base<_PTp*>::is_lock_free()): Call the built-in with the
	immediate pointer value, not a variable.
	* include/std/atomic (atomic<T>::is_lock_free()): Likewise.
	* testsuite/29_atomics/atomic/65913.cc: New.

From-SVN: r227878