[clang] [clang-cl] Support /stdc:latest (PR #147284)

[Corentin Jabot via cfe-commits]

================
@@ -248,7 +248,9 @@ C Language Changes
   not valid in C++.
 - The ``[[clang::assume()]]`` attribute is now correctly recognized in C. The
   ``__attribute__((assume()))`` form has always been supported, so the fix is
-  specific to the attribute syntax used.
+  specific to the attribute syntax used.'
+- The ``clang-cl`` driver now recognizes ``/stdc:latest`` and sets the language
+  mode to C23. #GH147233
----------------
cor3ntin wrote:

```suggestion
  mode to C23. (#GH147233)
```

(Not sure why we do this but we should be consistent)

https://github.com/llvm/llvm-project/pull/147284