separate idle hook

src/idle.c

@@ -30,8 +30,14 @@
 #include <rthw.h>
 #include <rtthread.h>
 
+#if defined (RT_USING_HOOK)
+#ifndef RT_USING_IDLE_HOOK
+#deifne RT_USING_IDLE_HOOK 1
+#endif
+#endif
+
 #ifndef IDLE_THREAD_STACK_SIZE
-#if defined (RT_USING_HOOK) || defined(RT_USING_HEAP)
+#if defined (RT_USING_IDLE_HOOK) || defined(RT_USING_HEAP)
 #define IDLE_THREAD_STACK_SIZE  256
 #else
 #define IDLE_THREAD_STACK_SIZE  128
@@ -44,7 +50,7 @@ static rt_uint8_t rt_thread_stack[IDLE_THREAD_STACK_SIZE];
 
 extern rt_list_t rt_thread_defunct;
 
-#ifdef RT_USING_HOOK
+#ifdef RT_USING_IDLE_HOOK
 static void (*rt_thread_idle_hook)();
 
 /**