Merge remote-tracking branch 'remotes/mst/tags/for_upstream' into staging

virtio fix for 2.4

Fixes migration in virtio 1 mode.
We still have a known bug with memory hotplug, it doesn't
look like we can fix that in time for 2.4.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
# gpg: Signature made Wed 05 Aug 2015 15:57:39 BST using RSA key ID D28D5469
# gpg: Good signature from "Michael S. Tsirkin <mst@kernel.org>"
# gpg:                 aka "Michael S. Tsirkin <mst@redhat.com>"

* remotes/mst/tags/for_upstream:
  virtio: fix 1.0 virtqueue migration

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>