[SCM] bs1770gain/master: Change order of avformat build dependency to prefer the ffmpeg version now the primary version in Debian unstable.

[Petter Reinholdtsen]

[Andreas Cadhalpun]
> libavformat-ffmpeg-dev isn't built anymore, so this won't work.  You
> should just remove it from the Build-Depends.

Aha.  Thank you for the tip.  Is this true also outside unstable, ie for
backports?

-- 
Happy hacking
Petter Reinholdtsen