Implement P0040R3, Extending memory management tools.

Implement P0040R3, Extending memory management tools.

	* include/bits/stl_uninitialized.h (utility): New include
	in C++17 mode.
	(uninitialized_default_construct): New.
	(uninitialized_default_construct_n): Likewise.
	(uninitialized_value_construct): Likewise.
	(uninitialized_value_construct_n): Likewise.
	(uninitialized_move): Likewise.
	(uninitialized_move_n): Likewise.
	(destroy_at, destroy, destroy_n): Likewise.
	* testsuite/20_util/specialized_algorithms/memory_management_tools/1.cc:
	New.

From-SVN: r240122