VIRTIO_F_IN_ORDER support for virtio devices

VIRTIO_F_IN_ORDER is a new feature presented in VIRTIO 1.1. As mentioned on the project description page, VIRTIO_F_IN_ORDER is a feature that devices and drivers can negotiate when the device uses descriptors in the same order in which they were made available by the driver. This feature can help devices and drivers batch buffers and improve performance. Currently the devices and drivers available in Linux and QEMU do not support the VIRTIO_F_IN_ORDER feature. The only implementation is available in DPDK for the virtio-net driver. I will spend this summer to implement VIRTIO_F_IN_ORDER feature in both Linux and QEMU, and in both split and packed virtqueue layouts. Patches will be sent as soon as possible.