message: Use util::to_string() in tests for Android compatibility
diff: @@ -189,7 +189,7 @@ struct StringifyingContext {
  return ss.str();
  }
  - std::string box(RowExpr row) { return std::to_string(row.get_index()); }
  + std::string box(RowExpr row) { return util::to_string(row.get_index()); }
  };
  namespace Catch {
  