[TASK] Remove some < PHP 7 quirks

Code snippets dedicated to PHP smaller than version 7 can
be removed after requirement has been raised.

Change-Id: Id04dca218e5d12c3e6d7d2a68fa8f88a812ccf0c
Resolves: #73674
Releases: master
Reviewed-on: https://review.typo3.org/46895


Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Alexander Opitz <opitz.alexander@googlemail.com>
Tested-by: Alexander Opitz <opitz.alexander@googlemail.com>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>