`algorithms/div/knuth`: Delegate to div_nxm_normalized if normalized.

*On 2022-10-24 @recmo wrote in [`fb3aa20`](https://github.com/recmo/uint/commit/fb3aa200dea389e2d1b0a23981da48a77a08b738) “Merge pull request #172 from recmo/div2”:*

Delegate to div_nxm_normalized if normalized.

```rust

let n = divisor.len();
let m = numerator.len() - n;

// Compute normalized divisor double-word and reciprocal.
// TODO: Delegate to div_nxm_normalized if normalized.
let (d, shift) = {
let d = u128::join(divisor[n - 1], divisor[n - 2]);
let shift = d.high().leading_zeros();
(
if shift == 0 {

```
*From [`src/algorithms/div/knuth.rs:96`](https://github.com/recmo/uint/blob/fb3aa200dea389e2d1b0a23981da48a77a08b738/src/algorithms/div/knuth.rs#L96)*