fix: check the correct XClassHint property
fix: check the correct XClassHint property

kudos to Arkadiusz Bokowy (this commit is a slightly changed version
of a patch sent to the devel-ml): when retrieving the '.res_name' of
a XClassHint we should check '.res_name' and not '.res_class'.

the other changes only reduce the code.

luebking/fluxbox,lukoko/fluxbox,luebking/fluxbox,Arkq/fluxbox,lukoko/fluxbox,olivergondza/fluxbox,olivergondza/fluxbox,naimdjon/fluxbox,Arkq/fluxbox,olivergondza/fluxbox,olivergondza/fluxbox,Arkq/fluxbox,lukoko/fluxbox,lukoko/fluxbox,luebking/fluxbox,lukoko/fluxbox,naimdjon/fluxbox,Arkq/fluxbox,naimdjon/fluxbox,Arkq/fluxbox,naimdjon/fluxbox,naimdjon/fluxbox,luebking/fluxbox,luebking/fluxbox,olivergondza/fluxbox