message: Add shape check for buffer_size with TFRecordDataset
diff: @@ -423,6 +423,8 @@ REGISTER_OP("TFRecordDataset")
  TF_RETURN_IF_ERROR(c->WithRankAtMost(c->input(0), 1, &unused));
  // `compression_type` could only be a scalar.
  TF_RETURN_IF_ERROR(c->WithRank(c->input(1), 0, &unused) );
  + // `buffer_size` could only be a scalar.
  + TF_RETURN_IF_ERROR(c->WithRank(c->input(2), 0, &unused) );
  return shape_inference::ScalarShape(c);
  });
  