!507 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 挑单到3.0分支

Merge pull request !507 from x_xiny/fix_pthread_mutex_lock

kal/posix/src/pthread_mutex.c

@@ -93,6 +93,7 @@ int pthread_mutex_destroy(pthread_mutex_t *mutex)
         return MapError(ret);
     }
     mutex->handle = _MUX_INVALID_HANDLE;
+    mutex->magic = 0;
     return 0;
 }