packaging: spec: use %exclude

I avoided using %exclude as I remembered that some rpm implementations
do not support that.

Then I remembered that it was the AIX rpm implementation... and we do
not support that for packaging.

Change-Id: Id697890aef516a8720c66862b43ec35fdb154cc0
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>