Update rtdef.h

Update version number to v4.0.1

include/rtdef.h

@@ -29,6 +29,7 @@
  * 2018-11-22     Jesven       add smp member to struct rt_thread
  *                             add struct rt_cpu
  *                             add smp relevant macros
+ * 2019-01-27     Bernard      change version number to v4.0.1
  */
 
 #ifndef __RT_DEF_H__
@@ -50,7 +51,7 @@ extern "C" {
 /* RT-Thread version information */
 #define RT_VERSION                      4L              /**< major version number */
 #define RT_SUBVERSION                   0L              /**< minor version number */
-#define RT_REVISION                     0L              /**< revise version number */
+#define RT_REVISION                     1L              /**< revise version number */
 
 /* RT-Thread version */
 #define RTTHREAD_VERSION                ((RT_VERSION * 10000) + \