Autotests Qml - fix compilation with Qt 5.9
Summary: BUG: 411197
Test Plan: Compile with Qt 5.9, e.g. on Ubuntu 18.04
Reviewers: Falkon, drosca
Reviewed By: Falkon, drosca
Subscribers: drosca, falkon
Tags: Falkon
Differential Revision: https://phabricator.kde.org/D27102