KPageView: remove invisible pixmap on right side of header
7bf344b5 removed support for showing icons on the page header, but missed to also clean up the code once added as work-around for misbehaviour in the Qt of that time by https://commits.kde.org/kdelibs/f4139df17092df5c685abeceb37a9a67b4d54441
Edited by Friedrich W. H. Kossebau