samba-tool dns: use bytes for inet_ntop

samba-tool dns: use bytes for inet_ntop

From Python's point of view, array.AddrArray is a list of byte-valued
integers. In Python 3 we can convert directly using the likes of

         bytes(array.AddrArray[i].MaxSa[8:24])

but in 4.10 we need to support both, so we use struct.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13965

Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Noel Power <npower@samba.org>
Autobuild-User(master): Noel Power <npower@samba.org>
Autobuild-Date(master): Wed May 29 11:29:17 UTC 2019 on sn-devel-184