added a new macro "SA6_IS_ADDR_UNSPECIFIED", which is a sockaddr_in6 version of IN6_IS_ADDR_UNSPECIFIED.
added a new macro "SA6_IS_ADDR_UNSPECIFIED", which is a sockaddr_in6 version
of IN6_IS_ADDR_UNSPECIFIED.

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