Fixing bug introduced in commit 827c9e84c3eac05ff0f448b2bc67be3cb397cf8e.

QCoreApplication::libraryPath can only be retrieved at runtime,
after the QCoreApplication object was constructed.

I learnt how to combine ArchLinux's makepkg with local repo
cloning and I'll stop to push untested changes just to improve my
workflow, because know (with new knowledge), my workflow is
unaffected.