Merge commit '96138e8c8da4b9397e627c934a33c22988d1192b'

* commit '96138e8c8da4b9397e627c934a33c22988d1192b':
  isom: only write the size if its non zero in mov_rewrite_dvd_sub_extradata()

Conflicts:
	libavformat/isom.c

See: b6ad5893ce
Merged-by: Michael Niedermayer <michaelni@gmx.at>