Make systemctl reference indirect in packaging/NetworkManager/30-winbind-systemd

Make systemctl reference indirect in packaging/NetworkManager/30-winbind-systemd

Some distributions have clever dependency generators when building packages
and generate dependencies for each executable called out in shell scripts.
The end result is that a package built out of samba would contain explicit dependency
to systemd even though it is usable without systemd.

Making systemctl reference indirect avoids explicit dependency.

Reviewed-by: Andreas Schneider <asn@samba.org>
Autobuild-User(master): Alexander Bokovoy <ab@samba.org>
Autobuild-Date(master): Fri Feb 22 18:18:20 CET 2013 on sn-devel-104