re PR other/31349 (gcc -v --help returns no options for C, C++)

re PR other/31349 (gcc -v --help returns no options for C, C++)

        PR other/31349
        * opts.c (undocumented_msg): Leave blank unless checking is
        enabled.
        (handle_options): Fix indentation.
        (print_filtered_help): If no language-specific options were
        displayed tell the user how to list all the options supported by
        the language's front-end.
        (print_specific_help): Fix indentation and remove duplicate line.
        (common_handle_option): Handle the -v option.
        For --help enable the display of undocumented options if the -v
        switch has been included on the command line.
        For --help= check for overlaps in the arguments between the option
        classes and the language names and issue a warning when they
        cannot be disambiguated.
        * c.opt (v): Pass on to the common option handler.

From-SVN: r132427