type_traits (is_null_pointer): Add.

type_traits (is_null_pointer): Add.

2013-05-02  Paolo Carlini  <paolo.carlini@oracle.com>

	* include/std/type_traits (is_null_pointer): Add.
	(__is_nullptr_t): Implement in terms of the latter.
	(is_fundamental, is_scalar): Adjust.
	* testsuite/20_util/is_null_pointer/requirements/
	explicit_instantiation.cc: New.
	* testsuite/20_util/is_null_pointer/requirements/typedefs.cc:
	Likewise.
	* testsuite/20_util/is_null_pointer/value.cc: Likewise.
	* testsuite/20_util/declval/requirements/1_neg.cc: Adjust dg-error
	line number.
	* testsuite/20_util/make_signed/requirements/typedefs_neg.cc:
	Likewise.
	* testsuite/20_util/make_unsigned/requirements/typedefs_neg.cc:
	Likewise.

From-SVN: r198516