QCursor::setPos() doesn't work for qpa

As of qtbase 8ef86d05f199ebab216da43d5e0a9dc322b657b3 , the QPA implementation of QCursor::setPos() seems to be a no-op:

void QCursor::setPos(int x, int y)
{
    // Need to check, since some X servers generate null mouse move
    // events, causing looping in applications which call setPos() on
    // every mouse move event.
    //
    if (pos() == QPoint(x, y))
        return;
}

Looks like it was copied from the QWS implementation and the last line was removed.

Some of Qt's autotests require a working QCursor::setPos(), so these will need to be adjusted for QPA if QCursor::setPos() is not implemented.