matroskaenc: Allow VP9 and Opus in webm

Bug-Id: 695

Signed-off-by: Anton Khirnov <anton@khirnov.net>
Merge commit 'd2ef708c95ace2518deffe830a9c439aeb9edd5d'

* commit 'd2ef708c95ace2518deffe830a9c439aeb9edd5d':
  matroskaenc: Allow VP9 and Opus in webm

Conflicts:
	libavformat/matroskaenc.c

See: 820ffaed0f64b7ec27275d093c6f81e181c86e94
Merged-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/cljr: require (v)strict -1 to use width %4 != 0

Suggested-by: kurosu
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>