[llvm] use multiplication with holes for 32-bit/64-bit clmul fallback (PR #203727)

[Folkert de Vries via llvm-commits]

https://github.com/folkertdev commented:

Lol I updated the riscv tests locally and 

> 5 files changed, 55626 insertions(+), 89048 deletions(-)

So I'll hold off on adding all of that until we're happy with the implementation.

https://github.com/llvm/llvm-project/pull/203727