Remove library dependency on libavformat
Remove library dependency on libavformat

The chromaprint library does not use any symbols from libavformat, so
the dependency is useless. Libavformat is used by the fpcalc tool and
the ffmpeg_audio_reader test, but libavformat is pulled in by other code
in these cases.

This was originally found in Debian where there were some issues caused
by the libavformat <-> libchromaprint circular dependency which was
created.

Debian Bug: https://bugs.debian.org/849484

lalinsky/chromaprint,capcomvertigo/chromaprint,lalinsky/chromaprint,capcomvertigo/chromaprint