`algorithms/mul_redc`: Improve

[github-actions[bot]]

On 2022-06-11 @recmo wrote in e80cbc5 “Merge pull request #136 from recmo/small-devex”:

Improve

use super::mul;
use core::iter::zip;

/// See Handbook of Applied Cryptography, Algorithm 14.32, p. 601.
#[allow(clippy::cognitive_complexity)] // REFACTOR: Improve
pub fn mul_redc(a: &[u64], b: &[u64], result: &mut [u64], m: &[u64], inv: u64) {
    debug_assert!(!m.is_empty());
    debug_assert_eq!(a.len(), m.len());
    debug_assert_eq!(b.len(), m.len());
    debug_assert_eq!(result.len(), m.len());

From src/algorithms/mul_redc.rs:5