A typo/copypaste error confusing p_es->p_dec with p_es->p_dec_record

w00t, my first CID fix :D

The extra_tags values were not duplicated.

It is not really needed and was complicating too much decoder code.

It allows faster seek and start up time when the access pace can be controlled.

The implementation design was broken. I will fix it once clock/decoder
API is more stable.

It is not perfect as the aout mixer buffers some data too but it is too
late...

No functionnal changes.