Included switch LWIP_UDPLITE (enabled by default) to switch off UDP-Lite support if not needed (reduces udp.c code size)

src/core/ipv4/ip.c

@@ -365,7 +365,9 @@ ip_input(struct pbuf *p, struct netif *inp) {
   switch (IPH_PROTO(iphdr)) {
 #if LWIP_UDP
   case IP_PROTO_UDP:
+#if LWIP_UDPLITE
   case IP_PROTO_UDPLITE:
+#endif
     snmp_inc_ipindelivers();
     udp_input(p, inp);
     break;