Adapt the cmake buildsystem to be able to work with KDE CI

Summary:
Mostly builds it again, it seems that some things were not up to date.
Also there's some workarounds that don't seem to be required, at least not
on our docker sdk.

Test Plan: Been building it in https://hub.docker.com/r/sgclark/kde-ci-android/

Reviewers: mutlaqja, ckertesz

Reviewed By: ckertesz

Subscribers: ckertesz, KDE Edu

Tags: KDE Edu

Differential Revision: https://phabricator.kde.org/D8859