gc+bytecode: Fully visit all instruction_list children

We accidentally stopped at the first child before m(

src/bytecode.c

@@ -64,7 +64,7 @@ apfl_gc_instructions_traverse(struct instruction_list *ilist, gc_visitor cb, voi
         case INSN_VAR_NEW:
             GET_ARGUMENT(ilist, i, arg);
             cb(opaque, GC_OBJECT_FROM(arg.string, GC_TYPE_STRING));
-            return;
+            break;
         }
     }
 }