Remove unnecessary library dependencies

This PR removes some extra dependencies added to libchromaprint.so.1 which are only needed for fpcalc and the testsuite. The commit messages are below:

• 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

• Remove library dependency on the audio processor library

  This library is only used by the fpcalc command so it does not need to be pulled in by the library itself.