[clang] [llvm] [WIP] Expand variadic functions in IR (PR #89007)

[Jon Chesterfield via llvm-commits]

JonChesterfield wrote:

I think the comments here are fed into https://github.com/llvm/llvm-project/pull/93362 successfully, will go through the list again to check.

https://github.com/llvm/llvm-project/pull/89007