[llvm] [IR] Add llvm `clmul` intrinsic (PR #140301)

[Oscar Smith via llvm-commits]

oscardssmith wrote:

@topperc looking at `TargetLoweringBase::initActions`, given that basically everything there listed explicitly wants to `Expand`, why aren't they all just in the big list that starts with `FGETSIGN`? Is there a reason some are separated out?

https://github.com/llvm/llvm-project/pull/140301