* include/bits/allocator.h (allocator<T>::is_always_equal): Define.
	* testsuite/20_util/allocator/requirements/typedefs.cc: Test for
	is_always_equal.
	* testsuite/util/testsuite_allocator.h
	(uneq_allocator::is_always_equal): Define as false_type.

From-SVN: r240920