Merge remote-tracking branch 'remotes/stefanha/tags/net-pull-request' into staging

Merge remote-tracking branch 'remotes/stefanha/tags/net-pull-request' into staging

Net patches

# gpg: Signature made Thu 04 Sep 2014 17:32:44 BST using RSA key ID 81AB73C8
# gpg: Good signature from "Stefan Hajnoczi <[email protected]>"
# gpg:                 aka "Stefan Hajnoczi <[email protected]>"

* remotes/stefanha/tags/net-pull-request:
  virtio-net: purge outstanding packets when starting vhost
  net: complete all queued packets on VM stop
  net: invoke callback when purging queue
  virtio: don't call device on !vm_running
  virtio-net: don't run bh on vm stopped
  net: Forbid dealing with packets when VM is not running

Signed-off-by: Peter Maydell <[email protected]>