I have checked the source code of the qmakeevaluator and the changes are present in version 5.9.1, still it does not recognize the platform. Even if I try to hardcode to the qmake evaluator the following:
1:I saw on google that someone else had this error with gcc 4.8. Upgrading solved it. Not saying it will for you. But was the only errors i could find in your log.
2: Sorry I don't know how to solve this. People are compiling for the PI but I never got around to try one
so the details of getting it to work is also unknown to me.
I have a good eye to https://www.ics.com/blog/configuring-qt-creator-raspberry-pi but no board so didnt try yet.