use the proper api to access the data structures

http://bugs.gentoo.org/225505

--- libiptc/libip6tc.c
+++ libiptc/libip6tc.c
@@ -113,7 +113,7 @@
 #include "libiptc.c"
 
 #define BIT6(a, l) \
- ((ntohl(a->in6_u.u6_addr32[(l) / 32]) >> (31 - ((l) & 31))) & 1)
+ ((ntohl(a->s6_addr32[(l) / 32]) >> (31 - ((l) & 31))) & 1)
 
 int
 ipv6_prefix_length(const struct in6_addr *a)
--- ip6tables.c
+++ ip6tables.c
@@ -678,7 +678,7 @@
 	for (i = 0, j = 0; i < n; i++) {
 		int k;
 		for (k = 0; k < 4; k++)
-			addrp[j].in6_u.u6_addr32[k] &= maskp->in6_u.u6_addr32[k];
+			addrp[j].s6_addr32[k] &= maskp->s6_addr32[k];
 		j++;
 		for (k = 0; k < j - 1; k++) {
 			if (IN6_ARE_ADDR_EQUAL(&addrp[k], &addrp[j - 1])) {