scripting/samba_upgradedns: Only look for IPv4/IPv6 addresses if we actually them

scripting/samba_upgradedns: Only look for IPv4/IPv6 addresses if we actually them

This allows the script to be used to create/remove the samba-specific dns-SERVER account
when we do not need to create the in-directory partition.

Andrew Bartlett

Reviewed-by: Stefan Metzmacher <metze@samba.org>
Autobuild-User(master): Stefan Metzmacher <metze@samba.org>
Autobuild-Date(master): Thu Jan 10 20:56:50 CET 2013 on sn-devel-104
(cherry picked from commit edbc26bca84ee77b5a9571ba8dc9416c0db25906)

Fix bug #9721 - samba_upgradedns patch for robustness (do not guess addresses
when just changing roles).