wrong audio pts on push-based audio outs due to incorrect driver delay calc

Important Information

Provide following Information:

• mpv version e6afc53e7cabf7d36aab4a8b25a6e2688e4449c8

Reproduction steps

Try to play audio-only files with push AOs. I could only test ao=null, ao=pulse, ao=alsa, but this should be reproducible on all of them I believe.

1. open mpv in play state so it has time to build up the audio queue

2. seek to EOF, or seek to EOF with --pause --loop (only with gapless audio but it's default)

3. the audio pts will always be off by +/- 0.2-3s, causing time-remaining to never be exactly zero or in the --loop case, it'll cause the the time-pos to be a negative value on the next loop

This is most likely because of broken delay calculation on push-based AOs.

Reproduce with ao=null, ao=pulse, or ao=alsa by building the audio queue, seeking to EOF, and checking the resulting PTS and time-remaining; for looping, check time-pos on the next loop. Trace the push-based audio-output driver delay calculation and consider the issue done when EOF timing is exact and loop positions do not become negative.