[libc][stdio] implement rename via SYS_renameat2 (llvm#86140)

SYS_rename may be unavailable on architectures such as aarch64 and
riscv.
rename can be implemented in terms of SYS_rename, SYS_renameat, or
SYS_renameat2. I don't have a full picture of the history here, but it
seems
that SYS_renameat might also be unavailable on some platforms.

`man 2 rename` mentions that SYS_renameat2 was added in Linux 3.15. We
don't
need to support such ancient kernel versions prior.

Link: llvm#84980
Link: llvm#85068

Author: nickdesaulniers

libc/src/stdio/linux/rename.cpp

@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "src/stdio/rename.h"
+#include "include/llvm-libc-macros/linux/fcntl-macros.h"
 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
 #include "src/__support/common.h"
 #include "src/errno/libc_errno.h"
@@ -15,7 +16,8 @@
 namespace LIBC_NAMESPACE {
 
 LLVM_LIBC_FUNCTION(int, rename, (const char *oldpath, const char *newpath)) {
-  int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_rename, oldpath, newpath);
+  int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_renameat2, AT_FDCWD, oldpath,
+                                              AT_FDCWD, newpath, 0);
 
   if (ret >= 0)
     return 0;

libc/test/src/stdio/rename_test.cpp

@@ -6,8 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "include/llvm-libc-macros/linux/unistd-macros.h"
 #include "include/llvm-libc-macros/linux/sys-stat-macros.h"
+#include "include/llvm-libc-macros/linux/unistd-macros.h"
 #include "src/errno/libc_errno.h"
 #include "src/fcntl/open.h"
 #include "src/stdio/rename.h"