N3421 C++1y Transparent functors

N3421 C++1y Transparent functors

	N3421 C++1y Transparent functors
	* include/bits/stl_function.h (plus<void>, minus<void>,
	multiplies<void>, divides<void>, modulus<void>, negate<void>,
	equal_to<void>, not_equal_to<void>, greater<void>, less<void>,
	greater_equal<void>, less_equal<void>, logical_and<void>,
	logical_or<void>, logical_not<void>, bit_and<void>, bit_or<void>,
	bit_xor<void>, bit_not<void>): Define.
	* doc/xml/manual/status_cxx2014.xml: Update.
	* testsuite/20_util/function_objects/comparisons_void.cc: New.

	* include/bits/stl_function.h: Implement N3421.
	* testsuite/20_util/function_objects/comparisons_void.cc: New.

From-SVN: r204290