modula2/108144 - Fix multilib install of libgm2

The following adjusts libgm2 to properly use the multilib build
infrastructure, thereby fixing the install with
--enable-version-specific-runtime-libs

In particular config-ml.pl needs to be applied to generated Makefiles
as documented in the manual and we have to avoid clobbering the
variables via make arguments.  The explicit install rules used different
ways to construct the multilib dir which isn't necessary and breaks
when MUTLIDIR is now finally set correctly.  Instead use
$(toolexeclibdir).

This results in some dead variables in the Makefile.am (and there were
some before), I refrained from doing even more changes here.

Verified with an install with and without --enable-version-specific-runtime-libs
and checking the result.

	PR modula2/108144
libgm2/
	* configure.ac: Apply config-ml.pl to the generated Makefiles.
	Set multilib_arg, use AM_PROG_LIBTOOL.
	* configure: Regenerate.
	* Makefile.am (AM_MAKEFLAGS): Do not override MULTI* flags.
	* Makefile.in: Regenerate.
	* libm2cor/Makefile.am: Install to $(toolexeclibdir)$(M2LIBDIR)
	rather than $(inst_libdir)/$(MULTIDIR)$(M2LIBDIR).
	* libm2iso/Makefile.am: Likewise.
	* libm2log/Makefile.am: Likewise.
	* libm2min/Makefile.am: Likewise.
	* libm2pim/Makefile.am: Likewise.
	* libm2cor/Makefile.in: Regenerate.
	* libm2iso/Makefile.in: Likewise.
	* libm2log/Makefile.in: Likewise.
	* libm2min/Makefile.in: Likewise.
	* libm2pim/Makefile.in: Likewise.