Fix build with gcc 4.8
When building current kstars with gcc 4.8, the build fails with errors
like this:
error: no matching function for call to
'ProfileWizard::connect(QPointer<QProgressDialog>&, void
(QProgressDialog::*)(),
ProfileWizard::detectStellarMate()::__lambda220)'
See also https://bugreports.qt.io/browse/QTBUG-48988
This patch fixes it, similar as in other applications, e.g.
https://cgit.kde.org/kdevelop.git/commit/?h=5.2&id=6d5bdbba0a04d7180bda1f6bb47acb386575a561
Differential Revision: https://phabricator.kde.org/D10086