packaging: setup: support classless IN-ADDR.ARPA delegation

support reverse query checking for RFC2317("Classless IN-ADDR.ARPA
delegation") type domain host.

recent version requires to set local host domain in /etc/hosts or
private DNS server. this update treats sub-delegated reverse zone,
which uses CNAME to forward NS.

Change-Id: I9f65fbc27992ddae0b3d01e19d317a2abe39db7b
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>
Signed-off-by: Mark Kachi <love.cairn@gmail.com>