[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.

Please regenerate the following test files (they should have reported errors when you ran `ninja check-llvm-codegen-x86`).
```
codegen-no-uselist-constantdata.ll
ctlz-gfni.ll
urem-seteq-illegal-types.ll
vec_insert-5.ll
vector-shuffle-combining.ll
```

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