Fix prop info fetching from prop slot with added hooks

Fixes GH-18268

Author: iluuu1994

Zend/tests/property_hooks/gh18268.phpt

@@ -0,0 +1,23 @@
+--TEST--
+GH-18268: array_walk() on object with added property hooks
+--FILE--
+<?php
+
+class A {
+    public $prop = 42;
+}
+
+class B extends A {
+    public $prop = 42 {
+        set {}
+    }
+}
+
+$b = new B;
+array_walk($b, function (&$item) {
+    var_dump($item);
+});
+
+?>
+--EXPECT--
+int(42)

Zend/zend_objects_API.c

@@ -203,7 +203,7 @@ ZEND_API void ZEND_FASTCALL zend_objects_store_del(zend_object *object) /* {{{ *
 
 ZEND_API ZEND_COLD zend_property_info *zend_get_property_info_for_slot_slow(zend_object *obj, zval *slot)
 {
-	uintptr_t offset = (uintptr_t)slot - (uintptr_t)obj->properties_table;
+	uintptr_t offset = (uintptr_t)slot - (uintptr_t)obj;
 	zend_property_info *prop_info;
 	ZEND_HASH_MAP_FOREACH_PTR(&obj->ce->properties_info, prop_info) {
 		if (prop_info->offset == offset) {