[llvm] [X86] Use GFNI for LZCNT vXi8 ops (PR #141888)

[Simon Pilgrim via llvm-commits]

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

Thanks for looking at this! 

Take a look at https://zig.godbolt.org/z/4GfbWajPT - the bit twiddling can be simplified to avoid the ANDNOT

https://github.com/llvm/llvm-project/pull/141888