[llvm] [DAG] Add ISD::CLMUL/H/R to isCommutativeBinOp (PR #176615)

[Simon Pilgrim via llvm-commits]

https://github.com/RKSimon requested changes to this pull request.

Not sure about riscv, but for x86 we'd be better off moving the test to the bottom of clmul.ll instead of a separate file - a commutative_clmul_v2i64 test added to clmul-vector.ll would be useful as well.

https://github.com/llvm/llvm-project/pull/176615