cmake COMPILER_HAS_AVX2_SUPPORT examples

espressomd/espresso cmake/espresso_enable_avx2_support.cmake :52

check_cxx_source_compiles(
    "#include <immintrin.h>
       __m256i xi_i = _mm256_set_epi32(1, 2, 3, 4, 5, 6, 7, 8);
       __m256  xi_s = _mm256_set_ps(0.f, 1.f, 2.f, 3.f, 4.f, 5.f, 6.f, 7.f);
       __m256d xi_d = _mm256_set_pd(0.0, 1.0, 2.0, 3.0);
       int main() {}
      " COMPILER_HAS_AVX2_SUPPORT)