c-cppbuiltin.c (c_cpp_builtin): Define __cpp_guaranteed_copy_elision and __cpp_nontype_template_parameter_auto.

	* c-cppbuiltin.c (c_cpp_builtin): Define __cpp_guaranteed_copy_elision
	and __cpp_nontype_template_parameter_auto.  Add a comment that
	__cpp_template_auto is deprecated.

	* g++.dg/cpp1z/feat-cxx1z.C: Add tests for
	__cpp_guaranteed_copy_elision and __cpp_nontype_template_parameter_auto
	feature test macros.
	* g++.dg/cpp2a/feat-cxx2a.C: Likewise.

From-SVN: r267925