Function safe_arch::truncate_to_i32_m128d_s

#[must_use]pub fn truncate_to_i32_m128d_s(a: m128d) -> i32

This is supported with target feature sse2 only.

Truncate the lower lane into an i32.

let a = m128d::from_array([1.7, 2.6]);
assert_eq!(truncate_to_i32_m128d_s(a), 1_i32);