add additional compatibility union member for ipv6 addresses

in6_* is in the reserved namespace, so this is valid

include/netinet/in.h

@@ -27,10 +27,12 @@ struct in6_addr
 {
 	union {
 		uint8_t __s6_addr[16];
+		uint16_t __s6_addr16[8];
 		uint32_t __s6_addr32[4];
 	} __in6_union;
 };
 #define s6_addr __in6_union.__s6_addr
+#define s6_addr16 __in6_union.__s6_addr16
 #define s6_addr32 __in6_union.__s6_addr32
 
 struct sockaddr_in6