alloc_traits.h (__allocator_always_compares_equal): New trait, provide partial specializations for known allocators.

2011-07-09  Jonathan Wakely  <jwakely.gcc@gmail.com>

	* include/ext/alloc_traits.h (__allocator_always_compares_equal): New
	trait, provide partial specializations for known allocators.
	(__alloc_traits::construct, __alloc_traits::destroy): Overload for
	non-standard pointer types.
	(__alloc_traits::_S_always_equal): New trait for use with noexcept.
	(__alloc_traits::_S_nothrow_move): Likewise.
	(__alloc_traits::_S_nothrow_swap): Likewise.

From-SVN: r176077