Re: [libvirt] [PATCH]: Export the 'label' on block devices

To keep code duplication down, I moved some of the enum's from storage_backend_disk.c into a common place. Note, however, that there is a slight semantic change because of this. Previously, if no label was found on a disk in storage_backend_disk.c, it would always return "dos" as the label type. That's not actually true, though; if it's a completely zeroed disk, for instance, it really just has label type of 'unknown'. This patch changes to the new semantic of 'unknown' for label types we don't understand. I don't think this will be a huge issue for compatibility, but there could be something I'm missing.