movenc: Do not flag secondary audio and subtitle tracks as enabled.

Fixes ticket #468 and ticket #1174.

Signed-off-by: Carl Eugen Hoyos <cehoyos@ag.or.at>
Merge remote-tracking branch 'cehoyos/master'

* cehoyos/master:
  movenc: Do not flag secondary audio and subtitle tracks as enabled.

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