Fix ref ID handling when serializing $GLOBALS

This was already broken previously, but in PHP 7.3 stricter
validation during unserialization made this into an error.

Author: nikic

ext/standard/tests/serialize/serialize_globals_var_refs.phpt

@@ -0,0 +1,22 @@
+--TEST--
+Reference IDs should be correctly generated when $GLOBALS is serialized
+--FILE--
+<?php
+
+$obj = new stdClass;
+$obj2 = new stdClass;
+$obj2->obj = $obj;
+$s = serialize($GLOBALS);
+$globals = unserialize($s);
+var_dump($obj);
+var_dump($obj2);
+
+?>
+--EXPECT--
+object(stdClass)#1 (0) {
+}
+object(stdClass)#2 (1) {
+  ["obj"]=>
+  object(stdClass)#1 (0) {
+  }
+}

ext/standard/var.c

@@ -959,9 +959,9 @@ static void php_var_serialize_intern(smart_str *buf, zval *struc, php_serialize_
 					/* we should still add element even if it's not OK,
 					 * since we already wrote the length of the array before */
 					if (Z_TYPE_P(data) == IS_ARRAY) {
-						if (Z_TYPE_P(data) == IS_ARRAY
-						 && (UNEXPECTED(Z_IS_RECURSIVE_P(data))
-						  || UNEXPECTED(Z_TYPE_P(struc) == IS_ARRAY && Z_ARR_P(data) == Z_ARR_P(struc)))) {
+						if (UNEXPECTED(Z_IS_RECURSIVE_P(data))
+							|| UNEXPECTED(Z_TYPE_P(struc) == IS_ARRAY && Z_ARR_P(data) == Z_ARR_P(struc))) {
+							php_add_var_hash(var_hash, struc);
 							smart_str_appendl(buf, "N;", 2);
 						} else {
 							if (Z_REFCOUNTED_P(data)) {