* include/std/tuple (tuple_size<cv _Tp>): Implement LWG 2313.
	* include/std/array (tuple_size, tuple_element): Add Doxygen comments.
	* include/std/utility (tuple_size, tuple_element): Likewise.
	* testsuite/23_containers/array/tuple_interface/tuple_element_neg.cc:
	Adjust dg-error line number.

From-SVN: r210470