[clang] [Clang] Fix Microsoft ABI inheritance model when member pointer is used in a base specifier (PR #91990)

[Max Winkler via cfe-commits]

================
@@ -598,7 +599,9 @@ class CXXRecordDecl : public RecordDecl {
     return !hasDefinition() || !isDynamicClass() || hasAnyDependentBases();
   }
 
-  void setIsParsingBaseSpecifiers() { data().IsParsingBaseSpecifiers = true; }
+  void setIsParsingBaseSpecifiers(bool to = true) {
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MaxEW707 wrote:

```suggestion
  void setIsParsingBaseSpecifiers(bool To = true) {
```

I am surprised clang-format didn't complain about starting with a lowercase for variables.
I can't think of a better name. I respond here if I do :).

https://github.com/llvm/llvm-project/pull/91990