[BUGFIX] Locallang file is not an XLIFF file in ext:extensionmanager

Resolves: #67849
Releases: master
Change-Id: I9b532c45322bad3e9d776326a3d9aa9257325175
Reviewed-on: http://review.typo3.org/40764


Reviewed-by: Stephan Großberndt <stephan@grossberndt.de>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>