[llvm] [X86] Use an FP-based expansion for v4i32 ctlz on SSE2-only targets (PR #167034)

[Simon Pilgrim via llvm-commits]

RKSimon wrote:

In the issue description i32 was converted to f64, are you sure it works in all cases with f32?

https://github.com/llvm/llvm-project/pull/167034