D15970: Properly look for fallback themes

[Eike Hein]

hein accepted this revision.

REPOSITORY
  R242 Plasma Framework (Library)

BRANCH
  master

REVISION DETAIL
  https://phabricator.kde.org/D15970

To: apol, #plasma, davidedmundson, hein
Cc: kde-frameworks-devel, michaelh, ngraham, bruns