Update pagebreak.php

[#33055] makes no sense to keep the adding point; With > php5.5 it would create a notice, because the $row->toc doesn't exist at that specific time.
Merge pull request #2742 from oe1tkt/patch-1

[#33055] Update pagebreak.php;  If pagebreak added to article a Notice: Undefined property: stdClass::$toc in pagebreak.php is created