Merge pull request #5242 from mysterywolf/revert-5199-removeselectpoll

[dfs] 保留dfs_poll.h dfs_select.h，加warning提示

components/dfs/include/dfs_poll.h

+/*
+ * Copyright (c) 2006-2021, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ */
+
+#ifndef DFS_POLL_H__
+#define DFS_POLL_H__
+
+#include <poll.h>
+
+#warning "This file will be obsolete in the next version! Please use <poll.h> to instead."
+
+#endif /* DFS_POLL_H__ */

components/dfs/include/dfs_select.h

+/*
+ * Copyright (c) 2006-2021, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ */
+
+#ifndef DFS_SELECT_H__
+#define DFS_SELECT_H__
+
+#include <sys/select.h>
+
+#warning "This file will be obsolete in the next version! Please use <sys/select.h> to instead."
+
+#endif