[clang] [clang][DebugInfo] Attach `DISubprogram` to additional call variants (PR #166202)

[J. Ryan Stinnett via cfe-commits]

jryans wrote:

> This is causing ~1.5% increase in bin size of clang when built internally in Google and ~1.8% increase in dwp file.

Thanks for the update. A bit more of an increase than [my own comparison](https://github.com/llvm/llvm-project/pull/166202#issuecomment-3481800307) above, but perhaps further optimisations, LTO modes, etc. are revealing more opportunities to insert this kind of debug info.

Since this is effectively fixing a debug correctness issue, we would want to retain the core fix here. If the size change is deemed to be too large, please open a new issue so we can use that to coordinate ways to reduce space, such as @djtodoro's suggestions above.

https://github.com/llvm/llvm-project/pull/166202