List view drag+drop broken in 3.1.2

[John Firebaugh]

The following change to qlistview.cpp makes it impossible to drag and drop 
multiple items. As soon as you press the right mouse button on a selected 
item to begin a drag, all other items are deselected.

@@ -4163,7 +4166,7 @@ void QListView::contentsMousePressEventE
        else if ( selectionMode() == Extended ) {
            bool changed = FALSE;
            if ( !(e->state() & (ControlButton | ShiftButton)) ) {
-               if ( !i->isSelected() ) {
+               if ( !i->isSelected() || e->button() != RightButton ) {
                    bool blocked = signalsBlocked();
                    blockSignals( TRUE );
                    clearSelection();

-John