添加rtthread相关代码

riscv/rtthread/components/libc/posix/delay/delay.h

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2006-2021, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ * 2021-05-07     Meco Man     first Version
+ */
+
+#ifndef __DELAY_H__
+#define __DELAY_H__
+
+unsigned int sleep(unsigned int seconds);
+void msleep(unsigned int msecs);
+void ssleep(unsigned int seconds);
+void mdelay(unsigned long msecs);
+void udelay(unsigned long usecs);
+void ndelay(unsigned long nsecs);
+
+#endif