QIconLoaderEngine: add missing Q_DECL_OVERRIDEs
QIconLoaderEngine: add missing Q_DECL_OVERRIDEs

Change-Id: I7671b05f2e3c218870dca04f3ed52c231dbe4a9d
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>

Port of:
https://code.qt.io/cgit/qt/qtbase.git/commit/src/gui/image?id=ef416e0faaa83cd122038db397dd24d949c9cafe

lxde/libqtxdg,lxde/libqtxdg,libqtxdg/libqtxdg,luis-pereira/libqtxdg,luis-pereira/libqtxdg,libqtxdg/libqtxdg