!396 fix:在非静态初始化条件下pthread_mutex_lock，没有经过init初始化就可以对已销毁的锁进行加锁

Merge pull request !396 from x_xiny/master

kal/posix/src/pthread_mutex.c

@@ -134,6 +134,7 @@ int pthread_mutex_destroy(pthread_mutex_t *mutex)
         return MapError(ret);
     }
     mutex->handle = _MUX_INVALID_HANDLE;
+    mutex->magic = 0;
     return 0;
 }