repair issue #461 (#487)

* repair issue #461

except branch idl_is_type_spec(node)

* if we add an "idl_is_type_spec(node)" branch, it will cause an infinite recursion...

* delete parse by automatic parser

src/idlcxx/src/generator.c

@@ -563,7 +563,7 @@ bool is_selfcontained(const void *node)
 {
   if (idl_is_sequence(node)
    || idl_is_string(node)
-   || idl_is_optional(node)) {
+   || is_optional(node)) {
     return false;
   } else if (idl_is_typedef(node)) {
     return is_selfcontained(((const idl_typedef_t*)node)->type_spec);