[llvm] [DataFlowSanitizer] Properly add ext attributes on arguments as needed. (PR #225443)

[Jonas Paulsson via llvm-commits]

JonPsson1 wrote:

> This is my first experience with this tool, and I was going to mention it in the actual commit message, but realize I should have also mentioned this in the PR description - sorry.

I think I will skip this now after all, as the suggestions made by Bob were basically replaced in the end.

https://github.com/llvm/llvm-project/pull/225443