Updated version of abcde to 2.5.4

- Added support for MusicBrainz queries to abcde package
- Added new dependencies to abcde: mkcue, eject, perl, MusicBrainz, MusicBrainzDiscID
- libdiscid version in pkg-config was incorrect; patched libdiscid to fix
- Added WebServices::MusicBrainz Perl module
- Added MusicBrainz::DiscID Perl module
- Commented out XSLoader Perl module since it was broken, no packages depend on it,
  and it has been incorporated into the Perl core