re PR preprocessor/60736 (Crash in preprocessor including stdc-predef.h when it does not exist on glibc-based systems)

	PR preprocessor/60736
	* include/cpplib.h (cpp_errno_filename): New prototype.
	* errors.c (cpp_errno): Don't handle msgid "" specially, use
	_(msgid) instead of msgid as argument to cpp_error.
	(cpp_errno_filename): New function.
	* files.c (read_file_guts): Use cpp_errno_filename instead of
	cpp_errno.
	(open_file_failed): Likewise.  Use file->name if file->path is NULL
	in diagnostics.

From-SVN: r230591