- added a new function in6_unlink_ifa() to release various links for   in6_ifaddr. - call it when attempt of address addition failed. this prevents a garbage   structure on such failures.
- added a new function in6_unlink_ifa() to release various links for
  in6_ifaddr.
- call it when attempt of address addition failed. this prevents a garbage
  structure on such failures.

MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame