QOpenGLWindow use after destruct

~QOpenGLWindowPrivate accesses QOpenGLWindow,
but the latter has already been destroyed when this
happens.
 
Detected by -sanitize undefined for this application:
 
#include <QApplication>
#include <QOpenGLWindow>

int main(int argc, char *argv[])
{
QApplication app(argc, argv);
QOpenGLWindow *window = new QOpenGLWindow();
delete window;
return app.exec();
{color:#3b3b3b}}