Function safe_arch::duplicate_odd_lanes_m256d

#[must_use]pub fn duplicate_odd_lanes_m256d(a: m256d) -> m256d

This is supported with target feature avx only.

Duplicate the odd-indexed lanes to the even lanes.

let a = m256d::from_array([1.0, 12.0, -1.0, 3.0]);
let c = duplicate_odd_lanes_m256d(a).to_array();
assert_eq!(c, [1.0, 1.0, -1.0, -1.0]);