[clang] [ItaniumMangle] Use mangleType instead of mangleNameOrStandardSubstitution in mangleCXXCtorVTable function (PR #109970)

[Younan Zhang via cfe-commits]

================
@@ -237,6 +237,11 @@ class LangOptionsBase {
     /// in the initializers of members of local classes.
     Ver18,
 
+    /// Attempt to be ABI-compatible with code generated by Clang 19.0.x.
+    /// This causes clang to:
+    ///   - Incorrect Mangling of CXXCtorVTable
----------------
zyn0217 wrote:

```suggestion
    ///   - Incorrectly mangle CXX vtable substitutions in some cases...
```

It would be great if you could flesh out the behavior changes here.



https://github.com/llvm/llvm-project/pull/109970