The shared libraries for macOS were obtained by first
installing/compiling the standard libraries using Homebrew:

  brew install libogg opus opusfile libopusenc libvorbis flac

These libraries were then copied into this directory.  However a
number of the libraries were looking for eachother internally.

The paths the libraries are currently expecting can be seen by
executing the command:

  otool -L *.dylib

This shows, for example:

  libopusfile.0.dylib:
    /usr/local/opt/opusfile/lib/libopusfile.0.dylib (compatibility version 5.0.0, current version 5.5.0)
    /usr/local/opt/libogg/lib/libogg.0.dylib (compatibility version 9.0.0, current version 9.4.0)
    /usr/local/opt/opus/lib/libopus.0.dylib (compatibility version 9.0.0, current version 9.0.0)
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1252.50.4)

Note the hard-coded location to libogg and libopus.  These files are
included with the PyOgg distribution, but not at those locations.

To fix the expected paths, we ran the following commands:

  install_name_tool -change /usr/local/opt/libogg/lib/libogg.0.dylib @loader_path/libogg.0.dylib libFLAC.8.dylib
  install_name_tool -change /usr/local/opt/opus/lib/libopus.0.dylib @loader_path/libopus.0.dylib libopusenc.0.dylib 
  install_name_tool -change /usr/local/opt/libogg/lib/libogg.0.dylib @loader_path/libogg.0.dylib libopusfile.0.dylib
  install_name_tool -change /usr/local/opt/opus/lib/libopus.0.dylib @loader_path/libopus.0.dylib libopusfile.0.dylib
  install_name_tool -change /usr/local/opt/libogg/lib/libogg.0.dylib @loader_path/libogg.0.dylib libvorbis.0.dylib
  install_name_tool -change /usr/local/Cellar/libvorbis/1.3.7/lib/libvorbis.0.dylib @loader_path/libvorbis.0.dylib libvorbisenc.2.dylib
  install_name_tool -change /usr/local/opt/libogg/lib/libogg.0.dylib @loader_path/libogg.0.dylib libvorbisenc.2.dylib
  install_name_tool -change /usr/local/Cellar/libvorbis/1.3.7/lib/libvorbis.0.dylib @loader_path/libvorbis.0.dylib libvorbisfile.3.dylib
  install_name_tool -change /usr/local/opt/libogg/lib/libogg.0.dylib @loader_path/libogg.0.dylib libvorbisfile.3.dylib

After changing the locations of the paths, we can rerun:

  otool -L *.dylib

Which shows, in the case of libopusfile:

  libopusfile.0.dylib:
    /usr/local/opt/opusfile/lib/libopusfile.0.dylib (compatibility version 5.0.0, current version 5.5.0)
    @loader_path/libogg.0.dylib (compatibility version 9.0.0, current version 9.4.0)
    @loader_path/libopus.0.dylib (compatibility version 9.0.0, current version 9.0.0)
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1252.50.4)

These relative paths mean the libraries will be found within the PyOgg
package.