Macro safe_arch::insert_m128d_to_m256d

macro_rules! insert_m128d_to_m256d {
    ($a:expr, $b:expr, $imm:expr) => { ... };
}

This is supported with target feature avx only.

Inserts an m128d to m256d

let a = m256d::from([0.0; 4]);
let b: [f64; 4] =
  insert_m128d_to_m256d!(a, m128d::from([3.0, 4.0]), 1).to_array();
assert_eq!(b, [0.0, 0.0, 3.0, 4.0]);