* common.opt (fwhopr=): Update for -fwhopr=jobserver
       * doc/invoke.texi (fwhopr): Document -fwhopr=jobserver.
       * lto-wrapper.c (run_gcc): Add jobserver mode.
       * opts.c (common_handle_option): Fix OPT_fwhopr for non numeric
         argument.

From-SVN: r163680