virtio: Add bool to VirtQueueElement

virtio: Add bool to VirtQueueElement

Add the boolean 'in_order_filled' member to the VirtQueueElement structure.
The use of this boolean will signify whether the element has been processed
and is ready to be flushed (so long as the element is in-order). This
boolean is used to support the VIRTIO_F_IN_ORDER feature.

Reviewed-by: Eugenio Pérez <eperezma@redhat.com>
Signed-off-by: Jonah Palmer <jonah.palmer@oracle.com>
Message-Id: <20240710125522.4168043-2-jonah.palmer@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>