message: Convert stringref to string explicitly
diff: @@ -1265,7 +1265,7 @@ Optional<std::string> Translator::TranslateInternal() {
  if (auto fn = dyn_cast<FuncOp>(op)) {
  if (fn != main_fn) {
  subgraph_index_map_[fn.getName().str()] = subgraph_idx++;
  - named_regions.emplace_back(fn.getName(), &fn.getBody());
  + named_regions.emplace_back(fn.getName().str(), &fn.getBody());
  }
  } else if (auto wo = dyn_cast<mlir::TFL::WhileOp>(op)) {
  std::string name = GetWhileCondName(wo);
  