enable IPv6 resolver support

lib/bind/port_after.h.in

@@ -64,6 +64,8 @@ struct sockaddr_in6 {
         struct in6_addr sin6_addr;      /* IPv6 address */
         u_int32_t       sin6_scope_id;  /* set of interfaces for a scope */
 };
+#else
+#define INET6 1
 #endif  /* HAS_INET6_STRUCTS */
 
 #if !defined(HAS_INET6_STRUCTS) || defined(NEED_IN6ADDR_ANY)