Remove quantum limitation from a2dp-sink, and adjust how flushing is
done.
The "low-latency" A2DP codecs are not able to flush all data at once, so
for them flush based on a timeout, such that "excess samples" for each
quantum is bounded. We also limit excess samples for the other A2DP
codecs, based on some testing on flaky headset/adapter combinations (for
most cases, this does not appear to matter).
Leave decision of packet sizes to the codecs. Currently, we send packets
based on min_latency, but sendinf full packets might help with stutter
on some headset/adapter combinations. The slightly increased latency
hardly matters against the 100ms delays in BT headsets.
Bump codec API version.
377bc16eb5