Add a "make rpmball" target

Add a "make rpmball" target

Build a simplistic dummy package, similar to "make debball", for
developers on rpm-based systems.

[ Fixed some trailing whitespace -iwj ]

Signed-off-by: George Dunlap <george.dunlap@eu.citrix.com>
CC: Ian Jackson <ian.jackson@citrix.com>
CC: Ian Campbell <ian.campbell@citrix.com>
CC: Dario Faggioli <dario.faggioli@citrix.com>
CC: Olaf Hering <olaf@aepfle.de>
CC: Don Slutz <dslutz@verizon.com>
CC: M A Young <m.a.young@durham.ac.uk>
Tested-by: Don Slutz <dslutz@verizon.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>