Function safe_arch::set_m128d_s

#[must_use]pub fn set_m128d_s(a: f64) -> m128d

This is supported with target feature sse2 only.

Sets the args into the low lane of a m128d.

let a = m128d::from_array([1.0, 0.0]);
let b = set_m128d_s(1.0);
assert_eq!(a.to_array(), b.to_array());