LU-1199 rpm: don't clean up $RPM_BUILD_ROOT in %build

LU-1199 rpm: don't clean up $RPM_BUILD_ROOT in %build

The %clean macro cleans up the buildroot. Doing it manually
makes the SUSE build system complain and breaks short-circuiting.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: James Simmons <uja.ornl@gmail.com>
Change-Id: I4a6b5ebfa34d9fcfddfb0608d4f7dcce3f88a3ef
Reviewed-on: http://review.whamcloud.com/5491
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Minh Diep <minh.diep@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>