Fix leak of backed_enum_table with preloading

Author: iluuu1994

Zend/zend_enum.c

@@ -187,6 +187,7 @@ void zend_enum_add_interfaces(zend_class_entry *ce)
 zend_result zend_enum_build_backed_enum_table(zend_class_entry *ce)
 {
 	ZEND_ASSERT(ce->ce_flags & ZEND_ACC_ENUM);
+	ZEND_ASSERT(!(ce->ce_flags & ZEND_ACC_IMMUTABLE));
 	ZEND_ASSERT(ce->type == ZEND_USER_CLASS);
 
 	uint32_t backing_type = ce->enum_backing_type;

Zend/zend_execute_API.c

@@ -346,6 +346,12 @@ ZEND_API void zend_shutdown_executor_values(bool fast_shutdown)
 				}
 			}
 
+			if (ce->type == ZEND_USER_CLASS && ce->backed_enum_table) {
+				ZEND_ASSERT(!(ce->ce_flags & ZEND_ACC_IMMUTABLE));
+				zend_hash_release(ce->backed_enum_table);
+				ce->backed_enum_table = NULL;
+			}
+
 			if (ce->ce_flags & ZEND_HAS_STATIC_IN_METHODS) {
 				zend_op_array *op_array;
 				ZEND_HASH_MAP_FOREACH_PTR(&ce->function_table, op_array) {