Mark failing tests as XFAIL for now

These test fail on Window since some recent changes to JIT; we mark
them as XFAIL until the issues are resolved.

Author: cmb69

Zend/tests/bug31098.phpt

@@ -1,5 +1,11 @@
 --TEST--
 Bug #31098 (isset() / empty() incorrectly returns true in dereference of a wrong type)
+--SKIPIF--
+<?php
+if (PHP_OS_FAMILY === 'Windows' && ini_get('opcache.jit') && ini_get('opcache.jit_buffer_size')) {
+    die('xfail unresolved issues with JIT on Windows');
+}
+?>
 --FILE--
 <?php
 $a = '';

Zend/tests/bug44660.phpt

@@ -1,5 +1,11 @@
 --TEST--
 Bug #44660 (Indexed and reference assignment to property of non-object don't trigger warning)
+--SKIPIF--
+<?php
+if (PHP_OS_FAMILY === 'Windows' && ini_get('opcache.jit') && ini_get('opcache.jit_buffer_size')) {
+    die('xfail unresolved issues with JIT on Windows');
+}
+?>
 --FILE--
 <?php
 $s = "hello";

ext/opcache/tests/jit/fetch_obj_001.phpt

@@ -7,6 +7,11 @@ opcache.file_update_protection=0
 opcache.jit_buffer_size=1M
 --SKIPIF--
 <?php require_once('skipif.inc'); ?>
+<?php
+if (PHP_OS_FAMILY === 'Windows' && ini_get('opcache.jit') && ini_get('opcache.jit_buffer_size')) {
+    die('xfail unresolved issues with JIT on Windows');
+}
+?>
 --FILE--
 <?php
 function foo(&$a) {