Since whipper's own "musicbrainz id calculation" fails on CDs with data
tracks on special places, the disc id calculation code is replaced with
libdiscid.
Gives a new way to calculate disc leadout or sectors (last sector of last
audio track) depends on whether the data track is placed last or not.
`discid` requires `len(track_offsets) != last - first + 1`.Which means
there can be only one data track in the disc and the lastTrack number is
deceptive.
For example: a disc (data audio audio audio) has firstTrack=1 lastTrack=3
which is wrong since according to the discid code :
"last **audio** track as :obj:`int"
it should be 4 but the firstTrack is always 1.
The code is duplicated with _getMusicBrainzValues function.
Signed-off-by: ABCbum <kimlong221002@gmail.com>