QTableWidgetItem uses additional enum flag ItemIsHeaderItem which has
the same numerical value as ItemFlag ItemNeverHasChildren.
This causes conflict since the user can set the latter flag using
the setFlags, while the ItemIsHeaderItem is only used internally
to mark header items.
Remove the additional flag and use boolean instead to fix the conflict.
Pick-to: 6.2 6.5 6.5.1
Fixes: QTBUG-113209
Change-Id: Icff549c7e452d9f84575a524361719204817274e
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
fa67cd0334