Function safe_arch::unpack_lo_m256d

#[must_use]pub fn unpack_lo_m256d(a: m256d, b: m256d) -> m256d

This is supported with target feature avx only.

Unpack and interleave the high lanes.

let a = m256d::from_array([1.0, 2.0, 3.0, 4.0]);
let b = m256d::from_array([59.0, 61.0, 79.0, 81.5]);
let c = unpack_lo_m256d(a, b).to_array();
assert_eq!(c, [1.0, 59.0, 3.0, 79.0]);