[BUGFIX] OOo to Sphinx converter fails with PHP 5.5

Change-Id: I51325b06b56c93a3b47cf3d8a3cd249f1b08943e
Fixes: #61582
Reviewed-on: http://review.typo3.org/32767
Reviewed-by: Xavier Perseguers <xavier@typo3.org>
Tested-by: Xavier Perseguers <xavier@typo3.org>