[rbp/omxplayer] Fix audio sync with visualisation

As GPU can buffer a few seconds of audio, and the visualisation is updated immediately, they are badly out of sync.
The solution is to push the visualisation data through a queue, and retrieve it from queue when the media time is reached.
Merge pull request #3049 from popcornmix/visualisation_sync

[rbp/omxplayer] Fix audio sync with visualisation