[llvm] Revert "LangRef: Clarify llvm.minnum and llvm.maxnum about sNaN and signed zero (#112852)" (PR #168838)

[Ralf Jung via llvm-commits]

RalfJung wrote:

I also found https://github.com/llvm/llvm-project/pull/138451 which proposes the same thing and has a bunch of discussion.

https://github.com/llvm/llvm-project/pull/168838