systemd-selinux: improve package quality

* Fix license directory path (found with namcap)
* Add "audit" as a dependency of systemd-selinux, needed by
  /usr/bin/systemd-analyze, /usr/lib/systemd/systemd and
  /usr/lib/systemd/systemd-update-utmp.
linux-selinux 3.17.3-1 update