functional (is_placeholder, [...]): Add partial specializations for cv-qualified...

functional (is_placeholder, [...]): Add partial specializations for cv-qualified types.

	* include/std/functional (is_placeholder, is_bind_expression): Add
	partial specializations for cv-qualified types.
	* include/tr1/functional (is_placeholder, is_bind_expression): Add
	partial specializations for std::bind and std::placeholders and for
	cv-qualified types.
	* testsuite/20_util/bind/cv_quals_3.cc: New.
	* testsuite/tr1/3_function_objects/bind/cv_quals.cc: New.
	* testsuite/tr1/3_function_objects/bind/mixed.cc: New.

From-SVN: r181607