Code review comment for lp:~raof/mir/client-release-simplifications

In this case, it no longer makes sense to have mir_buffer_stream_release_sync() so this should be deprecated. The mir_buffer_stream_release() should no longer have the callback and the context parameters (in other words, mir_buffer_stream_release_sync() should become mir_buffer_stream_release()).

The callback can then be eliminated.
169 + callback(stream, context);

I'm ok with following this up in another MP due to compatibility concerns. If you can make a note of this deprecation in alberto's client-api-deprecation branch, consider this approved.