Simplify Abstract type introspection

src/core/parse.c

@@ -624,9 +624,12 @@ static Janet parserget(void *p, Janet key);
 
 static JanetAbstractType janet_parse_parsertype = {
     "core/parser",
+    0,
     parsergc,
     parsermark,
     parserget,
+    NULL,
+    NULL,
     NULL
 };