[Gnash-dev] ffmpeg version for configure

[Rob Savoye]

I just checked in a configure patch that checks for the version of
ffmpeg that installed, since tgc tells me we need to use a new build.
Currently the threshold is the existence or not of
avcodec_decode_audio2(). This appears in ffmpeg 51.29.0, (current cvs is
at 51.32.0) Right now I have it just printing a warning till this
threshold is firmly agreed on through testing, but eventually it'll be a
configuration error.

I'm not sure if requiring a cvs build of ffmpeg is a good thing, so it'd
be nice if Gnash could work with a slightly older packaged version.

        - rob -