LibC: Add in6_addr and sockaddr_in6 structs

Libraries/LibC/netinet/in.h

@@ -54,4 +54,16 @@ struct sockaddr_in {
     char sin_zero[8];
 };
 
+struct in6_addr {
+    uint8_t s6_addr[16];
+};
+
+struct sockaddr_in6 {
+    uint16_t sin6_family;      // AF_INET6.
+    uint16_t sin6_port;        // Port number.
+    uint32_t sin6_flowinfo;    // IPv6 traffic class and flow information.
+    struct in6_addr sin6_addr; // IPv6 address.
+    uint32_t sin6_scope_id;    // Set of interfaces for a scop
+};
+
 __END_DECLS