Add empty-data optimization to Akonadi::CachePolicy.
Review Request #121404 - Created Dec. 9, 2014 and submitted
|dvratil, mlaurent, vkrause|
This showed up in heaptrack, but was actually due to another issue elsewhere. I still think this optimization does not hurt. But if you don't want this, it could be skipped, since the following optimizations will remove this as a hotspot anyways.