re PR libstdc++/65147 (alignment of std::atomic object is not correct)

re PR libstdc++/65147 (alignment of std::atomic object is not correct)

2015-04-09  Jonathan Wakely  <jwakely@redhat.com>
	    Richard Henderson  <rth@redhat.com>

	PR libstdc++/65147
	* include/bits/atomic_base.h (__atomic_base<_ITp>): Increase
	alignment.
	* include/std/atomic (atomic): For types with a power of two size set
	alignment to at least the size.
	* testsuite/29_atomics/atomic/60695.cc: Adjust dg-error line number.
	* testsuite/29_atomics/atomic/65147.cc: New.
	* testsuite/29_atomics/atomic_integral/65147.cc: New.

Co-Authored-By: Richard Henderson <rth@redhat.com>
From-SVN: r221945