Improve implementation of parallel equal()

Improve implementation of parallel equal()

	* include/pstl/algorithm_impl.h
	(__internal::__brick_equal): use "4 iterator" version of
	std::equal().
	(__internal::__brick_equal): use simd for random access
	iterators on unsequenced execution policies.
	(__internal::__pattern_equal): add "4 iterator" version
	(__internal::__pattern_equal): dispatch to simd __brick_equal
	for vector-only execution policies.
	(__internal::__pattern_equal): dispatch to __parallel_or for
	parallel execution policies.
	* include/pstl/glue_algorithm_impl.h
	(std::equal): dispatch to "4 iterator" version of
	__internal::__pattern_equal().

From-SVN: r270463