message: locked_queue: we can't use std::deferred
  It seems like with std::deferred this doesn't work as intended with
  older compilers.
diff: @@ -82,7 +82,7 @@ TEST(LockedQueue, ConcurrantAccess)
  auto prom = std::make_shared<std::promise<void>>();
  auto fut = prom->get_future();
  - auto some_future = std::async(std::launch::async | std::launch::deferred,
  + auto some_future = std::async(std::launch::async,
  [&prom, &locked_queue]() {
  // This will wait in the lock until the first item is returned.
  auto second_borrowed_item = locked_queue.borrow_front();
  @@ -96,7 +96,6 @@ TEST(LockedQueue, ConcurrantAccess)
  EXPECT_EQ(status, std::future_status::timeout);
  locked_queue.return_front();
  -
  - status = fut.wait_for(std::chrono::milliseconds(100));
  + status = fut.wait_for(std::chrono::milliseconds(10));
  EXPECT_EQ(status, std::future_status::ready);
  }
  