[libc] [llvm] [libc][c11] Add stdio.h's rename() function (PR #85068)

[Nick Desaulniers via llvm-commits]

================
@@ -0,0 +1,51 @@
+//===-- Unittests for rename ----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/fcntl/open.h"
+#include "src/stdio/rename.h"
+#include "src/unistd/access.h"
+#include "src/unistd/close.h"
+#include "test/UnitTest/ErrnoSetterMatcher.h"
+#include "test/UnitTest/Test.h"
+
+#include "src/errno/libc_errno.h"
+#include <unistd.h>
----------------
nickdesaulniers wrote:

What are you using from unistd.h? I think the test should be using definitions from within our libc.

https://github.com/llvm/llvm-project/pull/85068