Fixes video stutter on files with 120ms Opus audio frames (e.g. Amlogic
S905X4). DefaultAudioSink clamps getCurrentPositionUs to writtenDuration
which lags between bursts, creating a sawtooth pattern that drops video
frames. PositionFixAudioSink bypasses the clamp using the raw AudioTrack
position when the delegate falls behind.
edde746
d207185130