fix closure_destroy() with cast for AdjustAmountOfExternalAllocatedMemory()

src/closure.h

@@ -44,7 +44,7 @@ void
 closure_destroy(closure_t *closure) {
   if (closure->len) {
     free(closure->data);
-    V8::AdjustAmountOfExternalAllocatedMemory(-closure->max_len);
+    V8::AdjustAmountOfExternalAllocatedMemory(- (intptr_t) closure->max_len);
   }
 }