change back to using CONFIG_*_DEMUXER for ac3_eac3_probe(), but use it correctly this time.
change back to using CONFIG_*_DEMUXER for ac3_eac3_probe(), but use it
correctly this time.

git-svn-id: a4d7c1866f8397a4106e0b57fc4fbf792bbdaaaf@15147 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

prajnashi/ffmpeg,prajnashi/ffmpeg,prajnashi/ffmpeg,prajnashi/ffmpeg