[libc] fix that some function cannot be found in unistd.h

components/libc/compilers/common/extension/sys/unistd.h

@@ -1,57 +0,0 @@
-/*
- * Copyright (c) 2006-2021, RT-Thread Development Team
- *
- * SPDX-License-Identifier: Apache-2.0
- *
- * Change Logs:
- * Date           Author       Notes
- * 2020-12-16     Meco Man     add usleep
- * 2021-09-11     Meco Man     move functions from dfs_posix.h to unistd.h
- */
-
-#ifndef __SYS_UNISTD_H__
-#define __SYS_UNISTD_H__
-
-#include <stddef.h>
-#include "types.h" /* <sys/types.h> */
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-#define STDIN_FILENO    0       /* standard input file descriptor */
-#define STDOUT_FILENO   1       /* standard output file descriptor */
-#define STDERR_FILENO   2       /* standard error file descriptor */
-
-unsigned alarm(unsigned __secs);
-ssize_t read(int fd, void *buf, size_t len);
-ssize_t write(int fd, const void *buf, size_t len);
-off_t lseek(int fd, off_t offset, int whence);
-int pause(void);
-int fsync(int fildes);
-long sysconf(int __name);
-int unlink(const char *pathname);
-int close(int d);
-int ftruncate(int fd, off_t length);
-int rmdir(const char *path);
-int chdir(const char *path);
-char *getcwd(char *buf, size_t size);
-int access(const char *path, int amode);
-int pipe(int fildes[2]);
-int isatty(int fd);
-char *ttyname(int desc);
-unsigned int sleep(unsigned int seconds);
-int usleep(useconds_t usec);
-pid_t gettid(void);
-pid_t getpid(void);
-pid_t getppid(void);
-uid_t getuid(void);
-uid_t geteuid(void);
-gid_t getgid(void);
-gid_t getegid(void);
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif /* _SYS_UNISTD_H */

components/libc/compilers/common/extension/unistd.h

@@ -1,10 +0,0 @@
-/*
- * Copyright (c) 2006-2021, RT-Thread Development Team
- *
- * SPDX-License-Identifier: Apache-2.0
- *
- * Change Logs:
- * Date           Author       Notes
- */
-
-#include "sys/unistd.h"