Don't export QKeyFrame which is fully implemented in the header
This otherwise leads to inconsistent dll linkage warnigns on windows.
Change-Id: I4f32f2fd2cc45939187535b8232172b280df7316 Reviewed-by: Mike Krus mike.krus@kdab.com (cherry picked from commit 9d178917) Reviewed-by: Qt Cherry-pick Bot cherrypick_bot@qt-project.org