Merge modula-2 front end onto gcc.

Merge modula-2 front end onto gcc.

This commit merges the devel/modula2 into master.
The libraries reside in libgm2, the compiler in gcc/m2
and the testsuite in gcc/testsuite/gm2.

	* configure.ac (target_libraries): Add target-libgm2.
	Add NCN_STRICT_CHECK_TARGET_TOOLS entry for gm2.
	Add GCC_TARGET_TOOL entry for gm2.  (compare_exclusions)
	add gcc/m2/gm2-compiler/M2Version,
	gcc/m2/gm2-compiler-boot/SYSTEM and gcc/m2/gm2version.
	* Makefile.def (target_modules): Add libgm2.  (flags_to_pass)
	Add GM2_FOR_TARGET, GM2FLAGS_FOR_TARGET.  (dependencies) Add
	all-target-libgm2 and on=all-target-libatomic.  (languages)
	Add entry for language=m2 with gcc-check-target=check-m2
	and lib-check-target=check-target-libgm2.
	* Makefile.tpl (BUILD_EXPORTS): Add definition for GM2
	and GM2FLAGS.  (HOST_EXPORTS) Add definition for GM2.
	(BASE_TARGET_EXPORTS) Add definition for GM2.
	(GM2_FOR_BUILD) Defined.  (GM2FLAGS) Defined.
	(GM2_FOR_TARGET) Defined.  (GM2FLAGS_FOR_TARGET) Defined.
	(EXTRA_HOST_FLAGS) Defined.  (POSTSTAGE1_FLAGS_TO_PASS)
	Add GM2 and GM2_FOR_BUILD.  (EXTRA_TARGET_FLAGS) Add
	GM2 and GM2FLAGS.  (EXTRA_GCC_FLAGS) Add GM2_FOR_TARGET.

Signed-off-by: Gaius Mulley <gaiusmod2@gmail.com>