- in in6_unlink_ifa() always decrement the reference count of the associated   prefix.  otherwise, the prefix would never be purged after a manually   configured address expires. - initialized the lifetimes of a manually configured prefix correctly.
- in in6_unlink_ifa() always decrement the reference count of the associated
  prefix.  otherwise, the prefix would never be purged after a manually
  configured address expires.
- initialized the lifetimes of a manually configured prefix correctly.

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