Keeping the reference may end up in a crash if a created
QIcon outlives the QFileIconProvider and we then try to
generate a pixmap.
The reference is not necessary since the options are queried
only when creating the icon, so they can be saved in the icon
provider.
Task-number: QTBUG-46755
Change-Id: I5c60887c2ed39030a2a20298ff10fd652189e4e7
Reviewed-by: Timur Pocheptsov <Timur.Pocheptsov@digia.com>
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
Reviewed-by: Morten Johan Sørvig <morten.sorvig@theqtcompany.com>