If the prefixlength of an IPv6 VRRP VIP is 128, add the VIP as a deprecated address so Linux won't use it as a source address. If the prefixlength is other than 128, allow it to be used as a sourceaddress

Basically copied from http://marc.info/?l=keepalived-devel&m=130200733315039, by Leo Baltus.

FREE(add_str) after usage and fix indenting