[BUGFIX] #5178 Use time() instead of mktime()

Change-Id: I45bd05a85570f7daabb75b09501fbefbae23e9c4
Reviewed-on: http://review.typo3.org/34701
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: Oliver Klee <typo3-coding@oliverklee.de>