[llvm] [LLVM] Slay undead copysign code (PR #111269)

[via llvm-commits]

workingjubilee wrote:

I checked and the x87 float seems fine if this codepath is pruned. No visible regressions in LLVM's test suite. I mean, clang-format whines about my formatting again, but

https://github.com/llvm/llvm-project/pull/111269