Based on the synchronous QCOW file implementation present in the qcow
crate, we created a new qcow_sync module in block_util that ports this
synchronous implementation to the AsyncIo trait.
The point is to reuse virtio-blk asynchronous implementation for both
synchronous and asynchronous backends.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
