check liveness of cc->klass and cc->cme_

`cc->klass` and `cc->cme_` can be free'ed while last marking
so that it should be checked bofore updating the pointers.

gc.c

@@ -10128,17 +10128,14 @@ gc_ref_update_imemo(rb_objspace_t *objspace, VALUE obj)
       case imemo_callcache:
         {
             const struct rb_callcache *cc = (const struct rb_callcache *)obj;
-            if (cc->klass) {
+
+            if (!is_live_object(objspace, cc->klass) ||
+                !is_live_object(objspace, (VALUE)cc->cme_)) {
+                vm_cc_invalidate(cc);
+            }
+            else {
                 UPDATE_IF_MOVED(objspace, cc->klass);
-                if (!is_live_object(objspace, cc->klass)) {
-                    vm_cc_invalidate(cc);
-                }
-                else if (cc->cme_) { // cc->cme_ is available if cc->klass is given
-                    TYPED_UPDATE_IF_MOVED(objspace, struct rb_callable_method_entry_struct *, cc->cme_);
-                    if (!is_live_object(objspace, (VALUE)cc->cme_)) {
-                        vm_cc_invalidate(cc);
-                    }
-                }
+                TYPED_UPDATE_IF_MOVED(objspace, struct rb_callable_method_entry_struct *, cc->cme_);
             }
         }
         break;