Protobuf 3.15 adds a namespace alias for "pb" that conflicts with
Clementine's. Modify Clementine to use "cpb".
Patch provided by @ahesford
Reference: 5c028d6cf4/src/google/protobuf/port.h (L44)
Two problems here:
- the first was that "StartPlaybackLater" wasn't called from the thread which created SpotifyServer, so the timer never started.
- then the playback sometimes failed or started with an offset: just hack to ignore sourcedrained signal in this case.