Disable the test for a double wrap with IteratorIterator()

In HHVM, I can not detect this as there is no concept of running get_iterator()
on an object.

Author: derickr

tests/cursor/cursor-get_iterator-002.phpt

@@ -1,6 +1,7 @@
 --TEST--
 MongoDB\Driver\Cursor get_iterator handler does not yield multiple iterators (IteratorIterator)
 --SKIPIF--
+<?php if (defined("HHVM_VERSION_ID")) exit("skip HHVM cannot detect the *wrapping* of a Cursor"); ?>
 <?php require __DIR__ . "/../utils/basic-skipif.inc"; CLEANUP(STANDALONE) ?>
 --FILE--
 <?php