The capability also represents that 'blockdev-add' is functional. It's
necessary to detect it via presence of 'blockdev-del' since blockdev-add
did not have the unsupported 'x-blockdev-add' version previously and
thus would be marked as present even if we could not use it.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>