It's possible that this has some side effect on HipHop builds -- the require_once on UtfNormalDefines.php that had been moved from UtfNormalUtil.php to MediaWiki's Setup.php in r85944 had been previously damaged by r85327 sticking a MediaWiki-specific MWInit class static method call into it, making it break on all the generator & test & benchmark code which does not depend on MediaWiki.
With the require_once restored everything seems to work, though it's possible that it ends up trying to include twice on HipHop -- have not tested.
* @ingroup UtfNormal
*/
+/** */
+require_once dirname(__FILE__).'/UtfNormalDefines.php';
+
/**
* Return UTF-8 sequence for a given Unicode code point.
* May die if fed out of range data.