[libcxx] [llvm] Add C++23 stacktrace (P0881R7) (PR #136528)

[Hristo Hristov via llvm-commits]

================
@@ -0,0 +1,31 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_STACKTRACE_OSX_H
----------------
Zingam wrote:

```suggestion
#ifndef _LIBCPP_STACKTRACE_MACOS_H
```

Nit: I'd call this macOS.h since macOS isn't OSX for a while and this feature won't be available in any versions called OSX. So I think using "macOS" is more appropriate.

https://github.com/llvm/llvm-project/pull/136528