Use system-wide python-libvirt for vbmc
Use system-wide python-libvirt for vbmc

As not all hosts have libvirt-devel, python-devel or even gcc
installed and all should have python-libvirt, let's use system-wide
python packages as part of the virtualenv created for vbmc.
This way we won't need to install gcc, devel packages and some other
compile-time dependencies when installing python-libvirt in virtualenv.

aspiers/automation,SUSE-Cloud/automation,SUSE-Cloud/automation,aspiers/automation,gosipyan/automation,gosipyan/automation,aspiers/automation,gosipyan/automation,aspiers/automation,SUSE-Cloud/automation,SUSE-Cloud/automation,gosipyan/automation