ovz: Copy config by hands at restore

We need to find out veth names mapping, this is
best to be got from config, so prepare for getting
its line one-by-one.

Question -- what to do with veths configured, but
not saved in config?

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
ovz: Keep NETIF pairs in list for later restore req

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
restore: Get list of veth pairs from htype and put into req

After this the name of host-side veth link is preserved
during live migration.

TODO -- configured, but not saved link names should be
kept as well.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>