[llvm] [X86] Enable custom lowering of 256/512-bit vXi32 and vXi64 CLMUL nodes (PR #177554)

[Simon Pilgrim via llvm-commits]

RKSimon wrote:

That's what I'm looking at on #176879 - the main issue being efficiently concatenating nodes with different imm control bits.

https://github.com/llvm/llvm-project/pull/177554