Implement virtio_net link status (Mark McLoughlin)

Implement the VIRTIO_NET_F_STATUS feature by exposing the link status
through virtio_net_config::status.

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>



git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6250 c046a42c-6fe2-441c-8c8c-71466251a162
