Fix failure to run on system without GPU in CPU mode

[artyom-beilis]

When running caffe compiled with CUDNN in CPU mode on hardware without GPU it fails with errors like

 cudnn_conv_layer.cpp:52] Check failed: error == cudaSuccess (35 vs. 0)  CUDA driver version is insufficient for CUDA runtime version

Using Caffe default engine instead of CUDNN for CPU only mode fixes the issue

[Noiredd]

Can you elaborate on the issue? I cannot even compile Caffe with USE_CUDNN and CPU_ONLY together.

[artyom-beilis]

Can you elaborate on the issue? I cannot even compile Caffe with USE_CUDNN and CPU_ONLY together

I have one version of caffe build with CUDNN support - such that on machines with GPU I can start it in GPU mode and without one in CPU mode and of course I call set_mode(Caffe::CPU) or GPU accordingly

However it fails to run in CPU mode despite I asked to do prediction on CPU because all CUDNN layers do some initialization specific to gpu in LayerSetUp - something that caffe default layers don't do.

After this patch I can deploy caffe library on machine without GPU when I setup it in CPU mode.

[artyom-beilis]

The major goal is to deploy same build of Caffe on different machines regardless they have nVidia GPU or not.