When rows are hidden (implicitly or explicitly), then their layout data
does not get fully updated. If rows get hidden after the layout data has
been calculated once, then we must make sure that their indices are
reset. Otherwise we might access array indices that are out of bounds
when the layout data structure gets resized to fit only visible rows.
For good measure, skip entirely over hidden rows when accessing the
layout data when arranging the widget.
Fixes: QTBUG-109237
Pick-to: 6.5 6.4
Change-Id: I4d6943b6a110edb61f60ce78d31f0fc64b5cc03d
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>