[BUGFIX] Followup: Add compat to TYPO3 CMS 7 / Drop t3lib-usage

Never use "use"-statements in ext_localconf.php!
That will lead to problems when files are merged.
Followup to change-id I3ac2959554525950564b7af88bc48dbc320c9da9

Change-Id: I582b8ee46b691ec48c71562a26be0a1dfe5cc154
Resolves: #62788
Reviewed-on: http://review.typo3.org/34834
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Tested-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>