LIB-16: correct invalid negative offsets
LIB-16: correct invalid negative offsets

These are given by "copy-protected"/invalid discs.
In the examples the first track had an offset of -1.

Possibly some drives/drivers correct this automatically.

metabrainz/libdiscid,phw/libdiscid,metabrainz/libdiscid,phw/libdiscid