more readline breakage.

os/pl-rl.c

@@ -612,7 +612,11 @@ PL_install_readline(void)
 #else
   rl_basic_word_break_characters = ":\t\n\"\\'`@$><= [](){}+*!,|%&?";
 #endif
+#ifdef HAVE_RL_COMPLETION_FUNC_T
+  rl_add_defun("prolog-complete", prolog_complete, '\t');
+#else
   rl_add_defun("prolog-complete", (Function *)prolog_complete, '\t');
+#endif
 #if HAVE_RL_INSERT_CLOSE
   rl_add_defun("insert-close", rl_insert_close, ')');
 #endif