message: Use correct casts to get right dimensions on s390x
diff: @@ -1569,7 +1569,12 @@ Status ConcatShapeHelper(InferenceContext* c, int start_value_index,
  // Merge all the non-concat dims, and sum the concat dim to make an output
  // shape.
  - const int32 concat_dim = concat_dim_t->scalar<int32>()();
  + int64 concat_dim;
  + if (concat_dim_t->dtype() == DT_INT32) {
  + concat_dim = static_cast<int64>(concat_dim_t->flat<int32>()(0));
  + } else {
  + concat_dim = concat_dim_t->flat<int64>()(0);
  + }
  // Minimum required number of dimensions.
  const int min_rank = concat_dim < 0 ? -concat_dim : concat_dim + 1;
  