* cpperror.c (print_location): Don't special case <stdin>.
	(_cpp_begin_message): Handle WARNING_SYSHDR the same as
	WARNING, but we don't check if we're in system headers.
	* cpplib.h (enum error_type): WARNING_SYSHDR: New.
	* cpplib.c (do_warning): Warn in system headers.

From-SVN: r41186