[llvm] [FPEnv][AtomicExpand] Correct strictfp attribute handling in AtomicExpandPass (PR #87082)

[Matt Arsenault via llvm-commits]

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

I thought I fixed this in 3701ebe76b998a55993f605c2fb323c25cc0086b; why are those cases separate? 

https://github.com/llvm/llvm-project/pull/87082