Function _mm256_mask3_fmadd_pch
#[target_feature(enable = "avx512fp16", enable = "avx512vl")]
pub fn _mm256_mask3_fmadd_pch(a: __m256h, b: __m256h, c: __m256h, k: __mmask8) -> __m256hMultiply packed complex numbers in a and b, accumulate to the corresponding complex numbers in c,
and store the results in dst using writemask k (the element is copied from c when the corresponding
mask bit is not set). Each complex number is composed of two adjacent half-precision (16-bit)
floating-point elements, which defines the complex number complex = vec.fp16[0] + i * vec.fp16[1].