message: back out SetOp code refactoring which cause nn_grad_test unit test failures
diff: @@ -1920,7 +1920,8 @@ class MklPrimitiveFactory {
  void SetOp(const std::string& key, MklPrimitive* op) {
  auto &map = MklPrimitiveFactory<T>::GetHashMap();
  - CHECK(map.emplace(key, op).second);
  + auto stream_iter = map.find(key);
  + CHECK(stream_iter == map.end());
  map[key] = op;
  }
  