PR libstdc++/3181
	* include/c_std/std_cmath.h: #include <bits/cpp_type_traits.h>
	(acos): Handle integer argument.
	(asin): Likewise.
	(atan): Likewise.
	(atan2): Likewise.
	(ceil): Likewise.
	(cos): Likewise.
	(cosh): Likewise.
	(exp): Likewise.
	(fabs): Likewise.
	(floor): Likewise.
	(frexp): Likewise.
	(ldexp): Likewise.
	(log): Likewise.
	(log10): Likewise.
	(sin): Likewise.
	(sinh): Likewise.
	(sqrt): Likewise.
	(tan): Likewise.
	(tanh): Likewise.
	* include/bits/cpp_type_traits.h (__are_same<>): New traits.
	(__enable_if): Likewise.
	* testsuite/26_numerics/cmath/overloads.C: New test.

From-SVN: r66681