build: sync glusterfs.spec.in with Fedora glusterfs.spec

(this is the master branch)

* Sync with latest Fedora updates
* add glusterfs-libs RPM for RHEL6.5 oVirt/qemu-kvm, see BZ 916645

BUG: 950083
Change-Id: If5816f9b6a9478f6663c1de4d14a9f8341da9e84
Signed-off-by: Kaleb S. KEITHLEY <kkeithle@redhat.com>
Reviewed-on: http://review.gluster.org/5455
Reviewed-by: Vijay Bellur <vbellur@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>