Merge branch 'PHP-5.6' into PHP-7.0

* PHP-5.6:
  Prevent usage in GC after free.

Author: dstogov

Zend/zend_inheritance.c

@@ -657,7 +657,8 @@ static void do_inherit_property(zend_property_info *parent_info, zend_string *ke
 				int parent_num = OBJ_PROP_TO_NUM(parent_info->offset);
 				int child_num = OBJ_PROP_TO_NUM(child_info->offset);
 
-				zval_ptr_dtor(&(ce->default_properties_table[parent_num]));
+				/* Don't keep default properties in GC (thry may be freed by opcache) */
+				zval_ptr_dtor_nogc(&(ce->default_properties_table[parent_num]));
 				ce->default_properties_table[parent_num] = ce->default_properties_table[child_num];
 				ZVAL_UNDEF(&ce->default_properties_table[child_num]);
 				child_info->offset = parent_info->offset;