opt.h: Add LWIP_NETIF_CALLBACK (to avoid compiler warning) and set it to 0.

CHANGELOG

@@ -70,9 +70,12 @@ HISTORY
   * api_lib.c: Use memcpy in netbuf_copy_partial.
 
   ++ Bug fixes:
+  2007-03-21 Frédéric Bernon
+  * opt.h: Add LWIP_NETIF_CALLBACK (to avoid compiler warning) and set it to 0.
+
   2007-03-21 Frédéric Bernon
   * api_msg.c, igmp.c, igmp.h: Fix C++ style comments
-  
+
   2007-03-21 Kieran Mansley
   * opt.h Change default PBUF_POOL_BUFSIZE to accomodate default MSS +
     IP and TCP headers

src/include/lwip/opt.h

@@ -379,6 +379,11 @@ a lot of data that needs to be copied, this should be set high. */
 #define TCP_SNDLOWAT                    TCP_SND_BUF/2
 #endif
 
+/* Support network interface callbacks */
+#ifndef LWIP_NETIF_CALLBACK
+#define LWIP_NETIF_CALLBACK             0
+#endif
+
 /* Support loop interface (127.0.0.1) */
 #ifndef LWIP_HAVE_LOOPIF
 #define LWIP_HAVE_LOOPIF                0