Prevent rebuilding NLS (pot and gmo files) for more reproducible
builds.
* Patch Makefile.am to not rebuild NLS (i.e. pot and po files) so as
to generate more reproducible builds. Drop a patch that helped NLS
rebuilds (11-no-gettext-on-lua.diff), which obviously isn't
necessary if not rebuilding.
* Run just the clean target, not distclean, as the latter removes the
generated and distributed gmo files.