fix building when readline is disabled

--- a/builtins/complete.def
+++ b/builtins/complete.def
@@ -49,6 +49,8 @@ $END
 
 #include <config.h>
 
+#ifdef READLINE
+
 #include <stdio.h>
 
 #include "../bashtypes.h"
@@ -867,3 +869,5 @@ compopt_builtin (list)
 
   return (ret);
 }
+
+#endif