QHeaderView::mouseMoveEvent started autoscroll without propagating the
event's mouse position to QAbstractItemViewPrivate::draggedPosition.
This data member always containing QPoint() has lead to right drags not
causing an autoscroll at all. Left drags with a scroll offset just
kept scrolling until the offset was 0.
The missing propagation has been added.
As a drive by, dead code has been removed and the local variable pos
has been constified.
Fixes: QTBUG-113573
Pick-to: 6.6 6.5
Change-Id: I7b194dfc71abea6f2bbaaae18270c80eb15afb4d
Reviewed-by: Oliver Eftevaag <oliver.eftevaag@qt.io>
787b4c1506