[BUGFIX] Use dirname/basename from PathUtility

PathUtility methods dirname() & basename() instead of php functions

Resolves: #64309
Releases: master
Change-Id: I62e3c2c5cc0afafb4427f2d7c9f3df221b95c00d
Reviewed-on: http://review.typo3.org/36361


Reviewed-by: Thomas Deuling <tdeuling@gmail.com>
Tested-by: Thomas Deuling <tdeuling@gmail.com>
Reviewed-by: Michael Oehlhof <typo3@oehlhof.de>
Reviewed-by: Cedric Ziel <cedric@cedric-ziel.com>
Reviewed-by: Philipp Gampe <philipp.gampe@typo3.org>
Tested-by: Philipp Gampe <philipp.gampe@typo3.org>