Nova fails live migration when graphic addresses are not set to localhost or 0.0.0.0

[Pawel Koniszewski]

Description
===========
At some point pre-check for graphic addresses was moved to check_can_live_migrate_source, https://review.openstack.org/#/c/254709. However, this patch introduced regression, because it only moved a pre-check, but the data needed for the check is not populated at this point.

Steps to reproduce
==================
Setup with 2 compute nodes and live migration configured is enough.
1. Edit nova.conf and set vncserver_listen to, e.g., IP assigned to management interface on both compute nodes
2. Try to live migrate an instance

Expected result
===============
live migration will succeed regardless of IP address set in vncserver_listen (127.0.0.1, 0.0.0.0 or any IP assigned to one of interfaces on a compute node)

Actual result
=============
live migration fails:
Your libvirt version does not support the VIR_DOMAIN_XML_MIGRATABLE flag or your destination node does not support retrieving listen addresses. In order for live migration to work properly, you must configure the graphics (VNC and/or SPICE) listen addresses to be either the catch-all address (0.0.0.0 or ::) or the local address (127.0.0.1 or ::1).

Environment
===========
1. Exact version of OpenStack you are running
Trunk of nova, commit https://github.com/openstack/nova/commit/bebc86bf5598571a28dd47f17a05dd616fe0f550

2. Which hypervisor did you use?
QEMU/KVM + Libvirt

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/362756

[OpenStack Infra (hudson-openstack)]

Change abandoned by Pawel Koniszewski (<email address hidden>) on branch: master
Review: https://review.openstack.org/362756
Reason: Abandoning in favor of https://review.openstack.org/#/c/358599/