D10739: Remove deprecated cmake code

[Hannah von Reth]

vonreth added reviewers: kfunk, dfaure, vkrause, mlaurent.

REPOSITORY
  R246 Sonnet

REVISION DETAIL
  https://phabricator.kde.org/D10739

To: vonreth, kfunk, dfaure, vkrause, mlaurent
Cc: #frameworks, michaelh