[libvirt] patch for openvz driver to support vzctl 3.1

[Ilja Livenson]

Hi,

there was a recent update of vzctl from openvz, which made openvz
driver crash: https://www.redhat.com/archives/libvirt-users/2012-March/msg00203.html
Not sure about the correct procedure, but the patch is very simple and
is shown here: https://bugzilla.redhat.com/show_bug.cgi?id=809895 .

Basically, openvz dropped strict version numbering (3.1 vs 3.1.0),
which caused parsing to fail.

cheers,
Ilya