virtio-serial: save/load: Send target host connection status if different If the host connection to a port is closed on the destination machine after migration, whereas the connection was open on the source, the guest has to be informed of that. Similar for a host connection open on the destination. Signed-off-by: Amit Shah <amit.shah@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>