cmake HAVE_AVX2_INTRIN examples

InsightSoftwareConsortium/ITK Modules/ThirdParty/ZLIB/src/itkzlib-ng/cmake/detect-intrinsics.cmake :170

check_c_source_compiles(
        "#include <immintrin.h>
        __m256i f(__m256i x) {
            const __m256i y = _mm256_set1_epi16(1);
            return _mm256_subs_epu16(x, y);
        }
        int main(void) { return 0; }"
        HAVE_AVX2_INTRIN
    )