message: fix gko::dim warning on MSVC
diff: @@ -54,7 +54,7 @@ namespace gko {
  template <size_type Dimensionality, typename DimensionType = size_type>
  struct dim {
  static constexpr size_type dimensionality = Dimensionality;
  - friend class dim<dimensionality + 1>;
  + friend struct dim<dimensionality + 1>;
  using dimension_type = DimensionType;
  @@ -194,7 +194,7 @@ private:
  template <typename DimensionType>
  struct dim<1u, DimensionType> {
  static constexpr size_type dimensionality = 1u;
  - friend class dim<2>;
  + friend struct dim<2>;
  using dimension_type = DimensionType;
  