2013-04-22  Paolo Carlini  <paolo.carlini@oracle.com>

	* include/std/type_traits (is_signed): Simplify.
	* testsuite/20_util/make_signed/requirements/typedefs_neg.cc:
	Adjust dg-error line numbers.
	* testsuite/20_util/make_unsigned/requirements/typedefs_neg.cc:
	Likewise.
	* testsuite/20_util/declval/requirements/1_neg.cc: Likewise.