[BUGFIX] Allow lower case for drive letters on Windows in CLI scripts

Resolves: #61749
Releases: master, 6.2, 6.1
Change-Id: I88a3489311e8f94669876ddbe59589f68cd5708e
Reviewed-on: http://review.typo3.org/33320
Reviewed-by: Markus Klein <klein.t3@reelworx.at>
Tested-by: Markus Klein <klein.t3@reelworx.at>