D5623: fix build against Android NDK (API Level 21 is required)

[Aleix Pol Gonzalez]

apol accepted this revision.
This revision is now accepted and ready to land.

REPOSITORY
  R286 KFileMetaData

BRANCH
  master

REVISION DETAIL
  https://phabricator.kde.org/D5623

To: mgallien, #android, #frameworks, apol
Cc: apol, #frameworks