PySide Does Not Find Some Imports On OpenSuse

After the "Modernize cmake build" patch (97df448e) an ImporrtError showed up on Windows.
This was fixed by "Fix pyi generation on Windows" (8689054d).

The script generate_pyi.py was drastically rewritten and simplefied, and all imports of the script are now mandatory.

When trying to check this new version in, this error showed up:

ImportError: libimf.so: cannot open shared object file: No such file or directory 

This happens when the script tries to import QtCore. It has most probably a similar reason to happen as the Windows problem before: some path must be missing in CMake.