[clang] [win][clang] Align scalar deleting destructors with MSABI (PR #139566)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> Ok, I added the release note.
> 
> > we'd use ABI version tags for it at that point.
> 
> @AaronBallman Could you please elaborate a bit more on that?

We have a command line option, `-fclang-abi-compat=`, which lets the user say "I want to be ABI compatible with Clang version X". In code, we have `LangOptions::ClangABICompat` which tracks that information so we can either go down the "old path" or the "new path" as needed, like in: https://github.com/llvm/llvm-project/blob/edf636afe405ff90da7bf1834aa334bd52bc861e/clang/lib/AST/DeclCXX.cpp#L1002

https://github.com/llvm/llvm-project/pull/139566