In cases where cdrom_id does not go through the entire code path and one of the
probing functions returns -1 or exits early, the remaining variables were never
initialized. This caused effects like "phantom" audio CDs on empty drives, or
bogus data like ID_CDROM_MEDIA_TRACK_COUNT=22528.
Initialize the variables right away to avoid that.
Bug-Ubuntu: https://launchpad.net/bugs/559723