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

src/include/lwip/opt.h

@@ -348,6 +348,11 @@ a lot of data that needs to be copied, this should be set high. */
 #define LWIP_UDP                        1
 #endif
 
+/* Enable the UDP-Lite protocol (only makes sense if LWIP_UDP=1) */
+#ifndef LWIP_UDPLITE
+#define LWIP_UDPLITE                    1
+#endif
+
 #ifndef UDP_TTL
 #define UDP_TTL                         (IP_DEFAULT_TTL)
 #endif

src/include/lwip/udp.h

@@ -68,9 +68,11 @@ struct udp_pcb {
   /* ports are in host byte order */
   u16_t local_port, remote_port;
   
+#if LWIP_UDPLITE
   /* used for UDP_LITE only */
   u16_t chksum_len;
-  
+#endif /* LWIP_UDPLITE */
+
   /* addr and port are in same byte order as in the pcb */
   void (* recv)(void *arg, struct udp_pcb *pcb, struct pbuf *p,
     struct ip_addr *addr, u16_t port);