LU-9758 build: allow disabling lustre test and iokit rpm creation

LU-9758 build: allow disabling lustre test and iokit rpm creation

While attempting to create a basic set of rpms that didn't
include the lustre test and iokit rpm I encountered build
breakage. Test the lustre_test conditional in the spec file
so we don't attempt to build special lustre test rpms. The
lustre test rpm is actually dependant on the lustre iokit
rpm so if --disable-iokit is set we should disable lustre
test rpms generation as well.

Test-Parameters: trivial

Lustre-commit: f810a0b0c5af842c7e644f1e82594f1615e540e6
Lustre-change: https://review.whamcloud.com/27985

Change-Id: I39e215aa6816b782314c779ad6f752bf32a43341
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Reviewed-on: https://review.whamcloud.com/28372
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Minh Diep <minh.diep@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>