markobject
markobject(g, L); /* mark running thread */
markobject(g, rawtsvalue(o)); /* strings are `values', so are never weak */
markobject(g, mt);
markobject(g, gco2u(o)->env);
markobject(g, g->mt[i]);
markobject(g, g->mainthread);
markobject(g, h->metatable);
markobject(g, f->source);
markobject(g, f->upvalues[i].name);
markobject(g, f->p[i]);
markobject(g, f->locvars[i].varname);
markobject(g, cl->p); /* mark its prototype */
markobject(g, cl->upvals[i]);