[clang] [clang-cl] Fix value of __FUNCTION__ in MSVC mode. (PR #84014)

[via cfe-commits]

================
@@ -752,6 +760,8 @@ std::string PredefinedExpr::ComputeName(PredefinedIdentKind IK,
     PrintingPolicy Policy(Context.getLangOpts());
     PrettyCallbacks PrettyCB(Context.getLangOpts());
     Policy.Callbacks = &PrettyCB;
+    if (IK == PredefinedIdentKind::Function && ForceElaboratedPrinting)
+      Policy.SuppressTagKeyword = !LO.MicrosoftExt;
----------------
Sirraide wrote:

```suggestion
      Policy.SuppressTagKeyword = !LO.MSVCCompat;
```

https://github.com/llvm/llvm-project/pull/84014