* toolbar/gud-nexti.pbm, toolbar/gud-nexti.xpm
* toolbar/gud-step.pbm, toolbar/gud-step.xpm
* toolbar/gud-stepi.pbm, toolbar/gud-stepi.xpm: Renamed to
gud-n.*, gud-ni.*, gud-s.*, and gud-si.*, respectively, to avoid
file-name clashes on 8+3 filesystems.