Driver cleanup and purge of unnecessary code.

Driver cleanup and purge of unnecessary code.

This patch cleans up the driver gm2 by removing the old scaffold
support routines.  The driver is now much closer to other language
drivers with the exception of adding default libraries and include
paths if different dialects are chosen.

2022-06-22  Gaius Mulley  <gaius.mulley@southwales.ac.uk>

gcc/m2/ChangeLog:

        * m2/gm2-lang.cc (gm2_langhook_init_options_struct): Remove
        blank line.  (gm2_langhook_handle_option) purged options.
        (ftarget_ar) Removed.  (ftarget_ranlib) Removed.  (fmakeinit)
        Removed.  (fobject-path) Removed.  (fonlylink) Removed.
        * m2/gm2spec.cc (GM2_PREFIX_ENV): Removed.
        (add_exec_prefix) Removed.  (add_B_prefix) Removed.
        (get_objects) Removed.  (*get_link_args) Removed.  (*add_exec_dir)
        Removed.  (*add_exec_name) Removed.  (is_object) Removed.
        (remember_object) Removed.  (remember_link_arg) Removed.
        (scan_for_link_args) Removed.  (add_link_from_include) Removed.
        (check_gm2_root) Removed.  (*gen_gm2_prefix) Removed.
        (*gen_gm2_libexec) Removed.  (*get_libexec) Removed.
        (object_list) Removed.  (head_objects) Removed.
        (head_link_args) Removed.  (inclPos) Removed.
        (linkPos) Removed.  (seen_fonlylink) Removed.
        (seen_fmakeall0) Removed.  (seen_fmakeall) Removed.
        * m2/lang.opt: (fmakeinit) Removed.  (fobject-path) Removed.

libgm2/Changelog:

        * libm2pim/Makefile.am (M2MODS): Add M2Dependent.mod
        (M2DEFS) Add M2Dependent.def.

Signed-off-by: Gaius Mulley <gaius.mulley@southwales.ac.uk>