[clang] Fix Objective-C++ Sret of non-trivial data types on Windows ARM64 (PR #88671)

[Eli Friedman via cfe-commits]

https://github.com/efriedma-quic approved this pull request.

@davidchisnall Is this patch waiting for something?  (I got a request to check on the progress of this patch.)

https://github.com/llvm/llvm-project/pull/88671