[TASK] Change visibility of suhosin specific checks in SystemEnvironment

As the PHP extension suhosin is currently not distributed in a larger
manner (e. g. Debian dropped support), the checks for load status and
suhosin specific parameters in Install Tool are only displayed if the
extension is available and loaded.

Resolves: #64647
Releases: master, 6.2
Change-Id: Iac2e984031c84f28f2d41fb6cf69ffbe1d5f6045
Reviewed-on: http://review.typo3.org/36444


Reviewed-by: Benjamin Mack <benni@typo3.org>
Tested-by: Benjamin Mack <benni@typo3.org>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>