Mreged back changes that were lost during the savannah hack 3 weeks ago (using the sources from http://git.infradead.org/users/dwmw2/lwip.git)

src/include/lwip/api.h

@@ -168,12 +168,11 @@ struct netconn {
   /** maximum amount of bytes queued in recvmbox
       not used for TCP: adjust TCP_WND instead! */
   int recv_bufsize;
-#endif /* LWIP_SO_RCVBUF */
   /** number of bytes currently in recvmbox to be received,
       tested against recv_bufsize to limit bytes on recvmbox
-      for UDP and RAW
-      @todo: should only be necessary with LWIP_SO_RCVBUF==1 */
+      for UDP and RAW, used for FIONREAD */
   s16_t recv_avail;
+#endif /* LWIP_SO_RCVBUF */
   /** flags holding more netconn-internal state, see NETCONN_FLAG_* defines */
   u8_t flags;
 #if LWIP_TCP

src/include/lwip/opt.h

@@ -432,11 +432,14 @@
 #endif
 
 /**
- * ARP_QUEUEING==1: Outgoing packets are queued during hardware address
- * resolution.
+ * ARP_QUEUEING==1: Multiple outgoing packets are queued during hardware address
+ * resolution. By default, only the most recent packet is queued per IP address.
+ * This is sufficient for most protocols and mainly reduces TCP connection
+ * startup time. Set this to 1 if you know your application sends more than one
+ * packet in a row to an IP address that is not in the ARP cache.
  */
 #ifndef ARP_QUEUEING
-#define ARP_QUEUEING                    1
+#define ARP_QUEUEING                    0
 #endif
 
 /**