packaging: setup: Make versionlock optional

Do not edit it if there is nothing to put there.

Change-Id: I5e1bb5dff7a3b878ba09378a1f5e819c382684cb
Related-To: https://bugzilla.redhat.com/1080997
Related-To: https://bugzilla.redhat.com/1080998
Signed-off-by: Yedidyah Bar David <didi@redhat.com>