It simply tests the new OOB capability, and make sure the QAPISchema can
parse it correctly.

Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180326063901.27425-7-peterx@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>