Add missing return in nonvoid functions

Signed-off-by: François Andriot <francois.andriot@free.fr>
(cherry picked from commit 98a4338d07)

gtk2/kgtk2.c

@@ -1579,7 +1579,7 @@ gboolean gtk_file_chooser_set_filename(GtkFileChooser *chooser, const char *file
         realFunction = (void *(*)()) real_dlsym(RTLD_NEXT, "gtk_file_chooser_set_filename");
     realFunction(chooser, filename);
     if (((kgtkApp == APP_UNKNOWN) && BLACKLIST_UNKNOWN_GTK_APPS) || (kgtkApp == APP_BLACKLISTED) && realFunction) {
-        return;
+        return FALSE;
     }
 
 #ifdef KGTK_DEBUG
@@ -1693,7 +1693,7 @@ gboolean gtk_file_chooser_set_current_folder(GtkFileChooser *chooser, const gcha
         realFunction = (void *(*)()) real_dlsym(RTLD_NEXT, "gtk_file_chooser_set_current_folder");
     realFunction(chooser, folder);
     if (((kgtkApp == APP_UNKNOWN) && BLACKLIST_UNKNOWN_GTK_APPS) || (kgtkApp == APP_BLACKLISTED) && realFunction) {
-        return;
+        return FALSE;
     }
 
 #ifdef KGTK_DEBUG
@@ -1943,6 +1943,8 @@ GtkWidget * gtk_dialog_add_button(GtkDialog *dialog, const gchar *button_text, g
         printf("KGTK::gtk_dialog_add_button Overriding data->ok: %d\n", data->ok);
 #endif
     }
+
+    return NULL;
 }
 
 void gtk_dialog_add_buttons(GtkDialog *dialog, const gchar *first_button_text, ...)