[clang] [llvm] Fixes for SSAF user interface stack (PR #232475)

[Jan Korous via cfe-commits]

jkorous-apple wrote:

@steakhal I am not proposing to merge this, that's why I left it as a draft.
I was hoping if folks could tell me if they think the problems we hit on various build bots might be addressed or if they still see something missing. I consider that better than figuring it out experimentally by landing the individual commits.

I still plan to create individual PRs.

https://github.com/llvm/llvm-project/pull/232475