message: enhance bf16 compiler check logical.
  We found in some corner case, the build only failed at Ubuntu 18.04 + gcc 11.1.
  This PR will enhance bf16 logical to check compiler compatibility. And to guarantee build success.
diff: @@ -70,6 +70,12 @@ SET(AVX512_BF16_CODE "
  __m512 src;
  // detect avx512f and avx512_bf16
  _mm512_cvtneps_pbh(src);
  +
  + // Enhance check logical for Ubuntu 18.04 + gcc 11.1. Which compiler is not fully support BF16.
  + __m128 a;
  + __m128bh b;
  + b = _mm_cvtneps_pbh(a);
  +
  return 0;
  }
  ")
  