Forced audio start was left out when a third codec attempts to
start a second track transition. Only one pending transition is
allowed at a time. There wouldn't be enough PCM in the buffer to
trigger audio playback and audio would just return without giving
the pcm buffer a kick.

Fixes FS#13100 - Player failed on short tracks

Change-Id: I338b0b12022c591930451fd5ed26a2a73008835f