Remove redundant code paths for handling small values
Remove redundant code paths for handling small values

The implementation includes initial checks to determine whether
argument reduction is necessary. If possible, the implementation
uses small value approximations requiring less computation but
having equivalent floating-point accuracy. Without these checks,
argument reduction must handle these edge cases; e.g., when `f`
approximately equals `0` or when `f` is small. Because the
implementation includes these checks, the argument reduction code
paths handling these edge cases cannot be reached and are therefore
removed.

math-io/float64-log1p