Proper Cross Compile Installation

I have a clean install of Ubuntu 17.04 x 64 and QT 5.9.1. I followed the guide from https://github.com/Kukkimonsuta/rpi-buildqt and after some troubles I have my system now working properly and configured to cross compile for the Raspberry Pi 3. I extended this guide and have also compiled/installed all of QT 5.9.1 and now I would like to add Qwt. I don't do programming or system configuration on a regular basis so I'm a little confused and am hoping that I can get some help making the correct modifications to qwtconfig.pri.

Thanks in advance,
George