* commom.opt (Wfatal-errors): Add it.
* diagnostic.c (flag_fatal_errors): Define it.
(diagnostic_action_after_output): Check for flag_fatal_errors.
* flags.h (flag_fatal_errors): Declare it.
* opts.c (common_handle_option): Add OPT_Wfatal_errors.
* doc/invoke.texi (Warning Options): Document -Wfatal-errors.

From-SVN: r81323