Updated openstack/openstack
Project: openstack/nova  91ae986d158c06726af12eee0ea8a17fb71316ca

libvirt: add '_' prefix to remaining internal methods

Various methods are internal helpers so should have a '_'
prefix to indicate they are not part of public virt
driver API.

Related-bug: #1333219
Change-Id: I2996ccd188cc34a924f01d86a18c747465b7383f