QHeaderView: Application asked to unregister timer 0x2000001 which is not registered in this thread. Fix application.

The following small code snippet:

#include <QtGui>

int main(int argc, char **argv)
{
    QApplication app(argc, argv);

    QHeaderView headerView(Qt::Horizontal);
    headerView.setStretchLastSection(true);

    return 0;
}

results in the output "Application asked to unregister timer 0x2000001 which is not registered in this thread. Fix application."

The output is misleading, what is happening is that a timer is unregistered twice, once by ~QObject and once by ~QHeaderViewPrivate->~QBasicTimer

The attached patch fixes the warning.