[TASK] Improve wincache has() function

Change-Id: Ia90500734c71095c82f774ac6c0acd16ce28f096
Resolves: #42253
Releases: 6.0
Reviewed-on: http://review.typo3.org/16224
Reviewed-by: Philipp Gampe
Reviewed-by: Tomasz Krawczyk
Tested-by: Tomasz Krawczyk
Reviewed-by: Wouter Wolters
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn