[BUGFIX] Respect different options for layouts being not set

Since the core switches between 0 and empty as default values for
backend_layout and backend_layout_next_level we have to tackle both

Change-Id: I938283b7037fcac2886300daa61f91772d1b4aaf
Resolves: #60517
Reviewed-on: http://review.typo3.org/31770
Reviewed-by: Armin Ruediger Vieweg <armin@v.ieweg.de>
Tested-by: Armin Ruediger Vieweg <armin@v.ieweg.de>
Reviewed-by: Jo Hasenau <info@cybercraft.de>
Tested-by: Jo Hasenau <info@cybercraft.de>