message: Fix WorkQueue perf test
diff: template <typename T>
  double calculate_speedup(std::vector<int>& wait_times, int num_threads) {
  - auto wq = workqueue_mapreduce<int, int>(
  - [](int a) {
  - std::this_thread::sleep_for(T(a));
  - return a;
  - },
  - [](int a, int b) { return a + b; },
  - num_threads);
  + auto wq = workqueue_foreach<int>(
  + [](int a) { std::this_thread::sleep_for(T(a)); }, num_threads);
  for (auto& item : wait_times) {
  wq.add_item(item);
  }
  auto single_start = std::chrono::high_resolution_clock::now();
  - auto sum = 0;
  for (auto& item : wait_times) {
  std::this_thread::sleep_for(T(item));
  - sum += item;
  }
  auto single_end = std::chrono::high_resolution_clock::now();
  auto para_start = std::chrono::high_resolution_clock::now();
  - auto para_sum = wq.run_all();
  + wq.run_all();
  auto para_end = std::chrono::high_resolution_clock::now();
  - redex_assert(sum == para_sum);
  -
  double duration1 =
  std::chrono::duration_cast<T>(single_end - single_start).count();
  double duration2 =
  