Enable most optional libraries for sox

Enable most remaining optional libraries for package sox. Still
disabled are file/magic (needs a patch), ffmpeg (doesn't compile, will
be removed from next upstream version) and id3tag (not yet in MXE), as
well as the audio drivers for platforms other than Windows.
Enable use of optional libmagic for sox

Make sox use libmagic (package "file") for file type detection.
Requires two ugly hacks.
Merge pull request #154 from uklauer/sox-more-options

sox: enable most optional libraries