Updated to CUDA 9.1. And fixed no_gpu dependecies.

AlexeyAB

2018-02-23 cd2bdec09030edf7da79ecdeb38d908c106850b3

 src/network_kernels.cu

@@ -113,6 +113,13 @@
    state.delta = 0;
    state.truth = *net.truth_gpu;
    state.train = 1;
#ifdef CUDNN_HALF
   int i;
   for (i = 0; i < net.n; ++i) {
      layer l = net.layers[i];
      cuda_convert_f32_to_f16(l.weights_gpu, l.c*l.n*l.size*l.size, (half *)l.weights_gpu16);
   }
#endif
    forward_network_gpu(net, state);
   cudaStreamSynchronize(get_cuda_stream());
    backward_network_gpu(net, state);