[cpp] support rt-thread CPP wrapper sub-switch macros

components/libc/cplusplus/os/cxx_lock.h

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2006-2021, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2016/10/1      Bernard      The first version
+ */
+
+#pragma once
+
+#include <stdint.h>
+#include <string.h>
+
+namespace rtthread {
+
+class Lock
+{
+public:
+    Lock(Mutex& mutex) : m(mutex) {m.lock();}
+    ~Lock() {m.unlock();}
+
+protected:
+    Mutex &m;
+};
+
+}