[feature request] add example code for ideep on the pytorch_dnnl{,_dev} branch

I'd like to request for a simple `.cc` example file using `ideep` on the `pytorch_dnnl{,_dev}` branch.

Developers of some distributions, say Debian, won't include the sources from git submodules when doing the packaging. In that sense, these developers will need a way of sanity testing to ensure that the packaged `ideep` indeed works with the separately packaged onednn.

Thank you very much :-)

Start by checking the pytorch_dnnl and pytorch_dnnl_dev branches for existing ideep and oneDNN integration examples. Add a simple .cc example that can sanity-test separately packaged ideep with separately packaged oneDNN, then verify that it works on the relevant branch.

Written by the indexing model from the issue text.