avformat/movenc: added ability to use original stream ids as track ids instead of regenerating them

Sometimes it's useful to be able to define the exact track numbers in
the generated track, instead of always beginning at track id 1. Using
the option use_stream_ids_as_track_ids now copies the use stream ids
to track ids. Dynamically generated tracks (ie. tmcd) have their track
numbers defined as continuing from the highest numbered stream id.

Signed-off-by: Erkki Seppälä <erkki.seppala.ext@nokia.com>
Signed-off-by: OZOPlayer <OZOPL@nokia.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>