Feedback with OIDN install_deps.sh in Kubuntu 18.04

@StefanW any specific reason we look for common in build_files/cmake/Modules/FindOpenImageDenoise.cmake ?

I’ve installed oidn system wide and it seems like this is marked as not found for me.
However, if I remove it from the cmake file, oidn support is build properly and is working. So this seems to be unneeded