Fix compilation with current FFmpeg trunk

AVCODEC_MAX_AUDIO_FRAME_SIZE was deprecated and
finally removed from current trunk.

Initial patch by Lawrence D'Oliveiro (ldo) with
own modification, Thanks!

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@56058 954f8c5b-7b00-dc11-b283-0030488c597c