float-ratio-float returns 0 for numbers close to least-positive-float

Describe the bug

kernel::float-ratio-float returns zero (when underflows are disabled) for numbers that are just less least-positive float. I think the it should return the least-positive float value instead because it's closer than 0.

To Reproduce

Steps to reproduce the behavior:

1. Evaluate (kernel::float-ratio-float (/ 4 (expt 10 324)) 'double-float)
2. This returns 0d0

Expected behavior

I was kind of expecting 4\times 10^{-324} to be returned because that is closer to least-positive-double-float (4.9406564584124654d-324) than it is to 0.

We have the same issue with single-float's and double-double-float's.

Desktop (please complete the following information):

• OS: All
• Version: snapshot-2023-08

Additional context

Add any other context about the problem here.