[llvm] [X86] Remove redundant `cmp` before `adc` after `lzcnt` or `tzcnt` (PR #208392)

[via llvm-commits]

VachanVY wrote:

@phoebewang's review:
> I don't think the 32-bit testing anything related here. Maybe move i64 tests to a seperate file and test for 64-bit only?

But then we will have to move the i64 tests into separate files them. More splitting...

https://github.com/llvm/llvm-project/pull/208392