message: dnn: eliminate MSVC warnings from ngraph.hpp
diff: #ifdef HAVE_DNN_NGRAPH
  +#ifdef _MSC_VER
  +#pragma warning(push)
  +#pragma warning(disable : 4245)
  +#pragma warning(disable : 4268)
  +#endif
  #include <ngraph/ngraph.hpp>
  +#ifdef _MSC_VER
  +#pragma warning(pop)
  +#endif
  #endif // HAVE_DNN_NGRAPH
  