video: make track switching work for external images
Until now, this didn't work, since the external image had pts 0; so enabling video at a later time did nothing, because the image was discarded. Since hrseek now ends on the last frame (instead of nothing), reusing the hrseek mechanism solves this, and we don't even need to treat the cursed coverart case separately.
W
wm4 committed
4e74320320ea78904d94d11ffb35ef8f9f2b431e
Parent: 42c5867