Fix more warnings

thunar/thunar-clipboard-manager.c

thunar/thunar-file.c

thunar/thunar-icon-factory.c

thunar/thunar-list-model.c

thunar/thunar-path-entry.c

thunar/thunar-properties-dialog.c

thunar/thunar-renamer-model.c

thunar/thunar-renamer-pair.c

thunar/thunar-shortcuts-model.c

thunar/thunar-standard-view.c

thunar/thunar-tree-model.c

thunar/thunar-tree-view.c