Function _mm256_sign_epi8
#[target_feature(enable = "avx2")]
pub fn _mm256_sign_epi8(a: __m256i, b: __m256i) -> __m256iNegates packed 8-bit integers in a when the corresponding signed
8-bit integer in b is negative, and returns the results.
Results are zeroed out when the corresponding element in b is zero.