[clang] [clang-cl][AST] Fix auto NTTP MSVC 1920+ mangling for pointer types (PR #92477)

[Max Winkler via cfe-commits]

MaxEW707 wrote:

> Will llvm/lib/Demangle/MicrosoftDemangle.cpp also need to be updated? (That could be done separately)

Possibly. I didn't realize the llvm-project implemented demangling as well. I'll take a look at the demangle code after I merge this PR and get a separate PR up if it needs updating.

> Your commit message mentions variables, function pointers, and member function pointers... is there anything else we need to handle? Null pointers? Integers?

auto return functions that have NTTP parameters need fixing: https://github.com/llvm/llvm-project/issues/92204

Integers were fixed in this commit here: https://github.com/llvm/llvm-project/commit/83286a1a8f059d1664b64341854676a36a85cecd

I need to check null pointers.

I haven't checked C++20 float point or literal class types either.

https://github.com/llvm/llvm-project/pull/92477