Consolidate renameat Linux implementation

This patch consolidates the Linux renameat implementation on
sysdeps/unix/sysv/linux/renameat.c.  The renameat syscall was
deprecated at b0da6d44 for newer architectures, so using the
auto-generation list may generate wrappers that returns ENOSYS.

Current code try to use __NR_renameat and if it is not define
it uses __NR_renameat2.

Checked on x86_64 and aarch64.

	* sysdeps/unix/sysv/linux/renameat.c: New file.
	* sysdeps/unix/sysv/linux/syscalls.list: Remove renameat.