Fixed wait_stream flag, for compilation without GPU

AlexeyAB

2018-01-17 5a2a5679708c098a9d9d5973bc485f2e3c35c61d

 src/network.c

@@ -218,6 +218,7 @@
            state.delta = prev.delta;
        }
        layer l = net.layers[i];
        if (l.stopbackward) break;
        l.backward(l, state);
    }
}