Fixed FTBFS with clang.

Signed-off-by: Michele Calgaro <michele.calgaro@yahoo.it>

gtk2/kgtk2.c

@@ -1515,7 +1515,7 @@ gboolean gtk_file_chooser_select_filename(GtkFileChooser *chooser, const char *f
         realFunction = (void *(*)()) real_dlsym(RTLD_NEXT, "gtk_file_chooser_select_filename");
     realFunction(chooser, filename);
     if (((kgtkApp == APP_UNKNOWN) && BLACKLIST_UNKNOWN_GTK_APPS) || (kgtkApp == APP_BLACKLISTED) && realFunction) {
-        return;
+        return FALSE;
     }
 
 #ifdef KGTK_DEBUG