* tools/libvirt-guests.init.sh: Use only POSIX shell features, which
includes using gettext.sh for translation rather than $"".
* tools/Makefile.am (libvirt-guests.init): Supply a few more substitutions.
* po/POTFILES.in: Mark that libvirt-guests.init needs translation.
Signed-off-by: NEric Blake <eblake@redhat.com>