message: Fix evaluation on multi-GPUs: use network_eval_helper
diff: @@ -199,10 +199,10 @@ Error_t Session::eval() {
  embedding_->forward();
  if (networks_.size() > 1) {
  - // execute dense forward and backward with multi-cpu threads
  + // execute dense forward with multi-cpu threads
  for (unsigned int i = 0; i < networks_.size(); i++) {
  gpu_resource_group_.results[i] = gpu_resource_group_.train_thread_pool.push(
  - std::ref(network_train_helper), networks_[i]);
  + std::ref(network_eval_helper), networks_[i]);
  }
  for (unsigned int i = 0; i < networks_.size(); i++) {
  gpu_resource_group_.results[i].get();
  