添加rtthread相关代码

riscv/rtthread/components/legacy/dfs/dfs_select.h

@@ -0,0 +1,16 @@
+/*
+ * Copyright (c) 2006-2021, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2021-11-14     Meco Man     the first version
+ */
+
+#ifndef DFS_SELECT_H__
+#define DFS_SELECT_H__
+
+#include <sys/select.h>
+
+#endif /* DFS_SELECT_H__ */