Modula-2 support: Add the runtime library.

Modula-2 support: Add the runtime library.

* gnulib-local/m4/modula2.m4: New file.
* gnulib-local/modules/modula2: New file.
* gnulib-local/Makefile.am (EXTRA_DIST): Add modula2.m4 and the 'modula2'
module.
* autogen.sh (GNULIB_MODULES_RUNTIME_OTHER): Add modula2, modula2comp-script.
* gettext-runtime/intl-modula2/Libintl.def.in: New file.
* gettext-runtime/intl-modula2/Libintl.mod: New file.
* gettext-runtime/intl-modula2/LibintlFromC.def: New file.
* gettext-runtime/intl-modula2/Makefile.am: New file.
* gettext-runtime/intl-modula2/HACKING: New file.
* gettext-runtime/configure.ac: Invoke gt_MODULA2_CHOICE, gt_MODULA2COMP.
Determine VALUE_OF_LC_* for each LC_* constant. Set the variable BUILDMODULA2
and the Automake conditional BUILD_MODULA2.
* gettext-runtime/Makefile.am (SUBDIRS): Add intl-modula2.
* NEWS: Mention libintl_m2.so.
* gettext-runtime/NEWS: Likewise.
* PACKAGING: Add the interface and binary for the libintl_m2 library.
* DEPENDENCIES: Mention the Modula-2 compiler and runtime.