[TASK] Forbid media sections overlap when missing description

Add clearfix for prevent overlapping of media sections
in "about modules" module.

Resolves: #63258
Releases: master
Change-Id: I7c5906e088c4855570691464d61168f3df9b6cfb
Reviewed-on: http://review.typo3.org/34488
Reviewed-by: Mathias Schreiber <mathias.schreiber@wmdb.de>
Tested-by: Mathias Schreiber <mathias.schreiber@wmdb.de>
Reviewed-by: Xavier Perseguers <xavier@typo3.org>
Tested-by: Xavier Perseguers <xavier@typo3.org>