spec: add missing requirement for sanlock on el7

In the el7 section we were missing the sanlock and sanlock-python
requirements.

Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1064042
Change-Id: Icf9a6ae3386e4312861d7659da696f94498d7de4
Signed-off-by: Federico Simoncelli <fsimonce@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/25173
Reviewed-by: Dan Kenigsberg <danken@redhat.com>
Tested-by: Dan Kenigsberg <danken@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/25985
Tested-by: Douglas Schilling Landgraf <dougsland@redhat.com>
Reviewed-by: Yaniv Bronhaim <ybronhei@redhat.com>