* new macro to remove magic number - IPV6_ADDR_SCOPES_COUNT;
* sa6_checkzone() - this function checks sockaddr_in6 structure
for correctness of sin6_scope_id. It also can fill correct
value sometimes.
* in6_getscopezone() - this function returns scope zone id for
specified interface and scope.
* in6_getlinkifnet() - this function returns struct ifnet for
corresponding zone id of link-local scope.