merge from team/rizzo/astobj2 rev.47246

Same as for peers and users, replace ASTOBJ_UNREF(r, sip_registry_destroy)
with unref_registry(r);

Approved By: oej



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@47317 65c4cc65-6c06-0410-ace0-fbb531ad65f3