message: Change InterpConfig default constructor.
diff: @@ -506,8 +506,7 @@ struct InterpConfig
  static constexpr int conforming = -1; // helper value
  // Conforming face
  - // InterpConfig() : config(-1) { } // TODO: try to make this work with is_trivial
  - InterpConfig() = default;
  + InterpConfig() : config(conforming) { }
  // Non-conforming face, if nc_index is given assumes side==1 (always true
  // except for ghost faces)
  