add IDLE_THREAD_STACK_SIZE in rtconfig.h

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@1306 bbd45198-f89e-11dd-88c7-29a3b14d5316

src/idle.c

@@ -17,11 +17,13 @@
 #include <rtthread.h>
 #include "kservice.h"
 
+#ifndef IDLE_THREAD_STACK_SIZE
 #if defined (RT_USING_HOOK) || defined(RT_USING_HEAP)
 #define IDLE_THREAD_STACK_SIZE	256
 #else
 #define IDLE_THREAD_STACK_SIZE	128
 #endif
+#endif
 
 static struct rt_thread idle;
 ALIGN(RT_ALIGN_SIZE)