Implement #pragma GCC warning/error

Implement #pragma GCC warning/error

2012-10-04  Florian Weimer  <fweimer@redhat.com>

	* doc/cpp.texi (Pragmas): Document #pragma GCC warning, #pragma
	GCC error.

2012-10-04  Florian Weimer  <fweimer@redhat.com>

	* c-c++-common/cpp/diagnostic-pragma-1.c: New testcase.

2012-10-04  Florian Weimer  <fweimer@redhat.com>

	* directives.c (do_pragma_warning_or_error): New.
	(do_pragma_warning): New.
	(do_pragma_error): New.
	(_cpp_init_internal_pragmas): Register new pragmas.

From-SVN: r192084