[llvm] [RISCV] Guard CFI emission code with MF.needsFrameMoves() (PR #136060)

[Sam Elliott via llvm-commits]

https://github.com/lenary approved this pull request.

LGTM.

Sorry, going back over older LLVM PRs. I think the codegen is close enough right now that it's not an issue, but I would like the differences to be fixed.

This will likely need a rebase.

I did wonder if we should push the conditions into `CFIBuilder::insertCFIInst` but I don't think that's necessarily reasonable. It would be good if we didn't have to always remember the `if (NeedsDwarfCFI)` stuff inline.

https://github.com/llvm/llvm-project/pull/136060