Force correct extradata for AVID AVCI50 in mov.

Fixes ticket #2106.

Reviewed-by: Kieran Kunhya
Merge remote-tracking branch 'cehoyos/master'

* cehoyos/master:
  Force correct extradata for AVID AVCI50 in mov.

Merged-by: Michael Niedermayer <michaelni@gmx.at>