[BUGFIX] Warning in Install Tool if APC is installed but not enabled

Resolves: #53748
Releases: 6.2
Change-Id: I22a2b60871639075dc108946bbaeae3730fc7085
Reviewed-on: https://review.typo3.org/25493
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters