redhat: make rpms build on pre-f15 again

redhat: make rpms build on pre-f15 again

we don't have systemd everywhere. don't assume it

Reviewed-on: http://gerrit.openafs.org/5813
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Simon Wilkinson <sxw@inf.ed.ac.uk>
Tested-by: Simon Wilkinson <sxw@inf.ed.ac.uk>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
(cherry picked from commit 47b010d1e1d0e8bdbbcad73d5aedc19719d5d96a)

Change-Id: I200ca2306b0e6a22cdcb0515641977b2ea6d21a0
Reviewed-on: http://gerrit.openafs.org/6090
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>