[llvm] [IVDescriptors] Don't require nsz/nnan for (min|max)num. (PR #137003)

[Florian Hahn via llvm-commits]

fhahn wrote:

> t would certainly be nice for min/max reductions to vectorize without nonan, but generating 3 instructions for every fmin/fmax would be a shame too.

I guess with the new intrinsics definitions, generating `maxnum` for `fmax` is technically incorrect, and would have to be fixed regardless? Or if we accept to keep ignoring snans, we should also ignore them for reductions of maxnum, like gcc

https://github.com/llvm/llvm-project/pull/137003