muxer: Set media_time to the minimum Composition Time in the track.
muxer: Set media_time to the minimum Composition Time in the track.

This change does not cover Open RAP to prevent displaying undecodable leading samples but covers Closed RAP to display decodable leading samples in its sequence.

silverfilain/L-SMASH,l-smash/l-smash,silverfilain/L-SMASH,l-smash/l-smash,silverfilain/L-SMASH,l-smash/l-smash