We don't need to dup zend_class_constant here.

We don't need to dup zend_class_constant here.

quote why the internal class is still using duplication:
```
for internal classes, the zend_class_constant is malloc-ed. we need to
free it.

if (const->ce == ce) {
zval_ptr_dtor(&const->value);
free(const)
}
so, if two classes share one const, and it(parent class) was freed
before, this read(in child class, const->ce) is invalid..

and destroy_zend_class is called via zend_hash_destroy(class_table).
which is not in reverse order... so, parent classes are dtor first.

if we want this work, we should change that order.
```