[BUGFIX] Compare users lets current user disable herself

Starting from TYPO3 v7, the Backend module for user management does not let someone
mark herself as disabled (hidden=1).

The user comparison module should respect this behaviour and prevent it as well.

Resolves: #69944
Releases: master
Change-Id: Ie5fe9b8474b2a779f8ce515c3693e84ff1dce758
Reviewed-on: http://review.typo3.org/43419


Reviewed-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Tested-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Reviewed-by: Markus Sommer <markussom@posteo.de>
Tested-by: Markus Sommer <markussom@posteo.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>