Make dependency on libvirt dynamic

Fixes bug 1184960

Change-Id: If702807d9ae326bf216a2e076ce61062045d7c6b
diff --git a/files/rpms/nova b/files/rpms/nova
index c74f396..f50d93f 100644
--- a/files/rpms/nova
+++ b/files/rpms/nova
@@ -7,9 +7,9 @@
 iptables
 iputils
 kpartx
-kvm
+kvm # NOPRIME
 libvirt-bin # NOPRIME
-libvirt-python
+libvirt-python # NOPRIME
 libxml2-python
 numpy # needed by websockify for spice console
 m2crypto