add __RT_SERVICE_H__ definition

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@2347 bbd45198-f89e-11dd-88c7-29a3b14d5316

include/rtservice.h

@@ -15,6 +15,9 @@
  * 2012-03-22     Bernard      rename kservice.h to rtservice.h
  */
 
+#ifndef __RT_SERVICE_H__
+#define __RT_SERVICE_H__
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -105,3 +108,5 @@ rt_inline int rt_list_isempty(const rt_list_t *l)
 #ifdef __cplusplus
 }
 #endif
+
+#endif