Issue #20374: Avoid compiler warnings when compiling readline with libedit.

Modules/readline.c

@@ -773,15 +773,24 @@ on_hook(PyObject *func)
     return result;
 }
 
+
 static int
+#if defined(_RL_FUNCTION_TYPEDEF)
 on_startup_hook(void)
+#else
+on_startup_hook()
+#endif
 {
     return on_hook(startup_hook);
 }
 
 #ifdef HAVE_RL_PRE_INPUT_HOOK
 static int
+#if defined(_RL_FUNCTION_TYPEDEF)
 on_pre_input_hook(void)
+#else
+on_pre_input_hook()
+#endif
 {
     return on_hook(pre_input_hook);
 }