remove compiling warning

components/pthreads/mqueue.c

@@ -21,6 +21,7 @@
  * Date           Author       Notes
  */
 
+#include <string.h>
 #include "mqueue.h"
 #include "pthread_internal.h"
 

components/pthreads/semaphore.c

@@ -23,6 +23,7 @@
  */
 
 #include <rtthread.h>
+#include <string.h>
 #include "semaphore.h"
 #include "pthread_internal.h"