fixed a compiling error, if RT_LWIP_PBUF_POOL_BUFSIZE isn't defined in rtconfig.h:

drivers\luminaryif.c(48): error:  #59: function call is not allowed in a constant expression

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@2102 bbd45198-f89e-11dd-88c7-29a3b14d5316

bsp/lm3s8962/rtconfig.h

@@ -150,4 +150,8 @@
 #define RT_LWIP_ETHTHREAD_PRIORITY		23
 #define RT_LWIP_ETHTHREAD_MBOX_SIZE		4
 #define RT_LWIP_ETHTHREAD_STACKSIZE		512
+
+/* the size of each pbuf in the pbuf pool. */
+#define RT_LWIP_PBUF_POOL_BUFSIZE		1500
+
 #endif

bsp/lm3s9b9x/rtconfig.h

@@ -154,5 +154,7 @@
 /* TCP receive window. */
 #define RT_LWIP_TCP_WND		8192
 
+/* the size of each pbuf in the pbuf pool. */
+#define RT_LWIP_PBUF_POOL_BUFSIZE	1500
 
 #endif