other audio codecs rather than only AC-3, so add some code that makes
word byte-swapping only happen for AC-3, not for all audio codecs.

Patch by Francesco Lavra <francescolavra interfree it>.



git-svn-id: file:///var/local/repositories/ffmpeg/trunk@23361 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b