Create a common core that comprises the actual meat of what the backup API
boundary needs to do, and then switch drive-backup to use it.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190709232550.10724-3-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
