To draw a CE_ItemViewItem QStyleSheetStyle::drawControl lets parts
of the element being drawn by QWindowsStyle, others by baseStyle().
If the ItemViewItem has an icon, it can lead to the icon being drawn
twice: Once by QWindowsStyle, respecting options set in the stylesheet.
Once by the baseStyle(), not respecting stylesheet options.
When the style sheet modifies the icon's position, the icon will be
drawn at this position as well as on the default position.
This patch prevents an icon to be drawn by baseStyle() when it has
already been drawn by the QWindowsStyle.
Fixes: QTBUG-110942
Pick-to: 6.6 6.5
Change-Id: I8622dfe95bef13b196a3e38025fac1cc92f097c9
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>