[clang] [llvm] [LLVM] Respect `optnone` in `promote-args` and `deadargelim` (PR #211804)

[Nikita Popov via cfe-commits]

nikic wrote:

Rather than adding a new helper that is only checked in 20% of the necessary places, can you hook this into isInterposable() similar to the noipa handling?

https://github.com/llvm/llvm-project/pull/211804