[llvm] [GISel] Extend ConstantFoldFPBinOp with fminimumnum, fmaximumnum, fix frem vs fmod (PR #190561)

[Tim Gymnich via llvm-commits]

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tgymnich wrote:

@arsenm shouldn't this apply to `G_FMAXNUM` instead of `G_FMAXNUM_IEEE` which does stick to ieee semantics?

https://github.com/llvm/llvm-project/pull/190561