[llvm] [llvm] Add support for llvm IR atomicrmw fminimum/fmaximum instructions (PR #136759)

[Jonathan Thackray via llvm-commits]

jthackray wrote:

Thanks for your comments, @nikic and @arsenm. I think I've fixed them all. Are there any more changes required before merging? 

https://github.com/llvm/llvm-project/pull/136759