build broken with Dali head 8f41ea5

[byzhang]

Here is the error

dali-examples/examples/bidirectional_sentiment.cpp: In instantiation of ‘std::tuple<Mat<R>, Mat<R> > BidirectionalLSTM<T>::activate_sequence(Indexing::Index, T) [with T = float]’:
dali-examples/examples/bidirectional_sentiment.cpp:526:9:   required from here
dali-examples/examples/bidirectional_sentiment.cpp:254:51: error: ‘conv1d’ is not a member of ‘MatOps<float>’
                 auto convolved = MatOps<T>::conv1d(
                                                   ^