Function _mm256_mulhrs_epi16
#[target_feature(enable = "avx2")]
pub fn _mm256_mulhrs_epi16(a: __m256i, b: __m256i) -> __m256iMultiplies packed 16-bit integers in a and b, producing
intermediate signed 32-bit integers. Truncate each intermediate
integer to the 18 most significant bits, round by adding 1, and
return bits [16:1].