D19420: Fix KCompressionDevice::atEnd() for uncompressed .gz files

[Kai Uwe Broulik]

broulik added a reviewer: Frameworks.

REPOSITORY
  R243 KArchive

REVISION DETAIL
  https://phabricator.kde.org/D19420

To: croick, broulik, #frameworks
Cc: kde-frameworks-devel, michaelh, ngraham, bruns