Convert a TrackDescription linked list to a Python list (and release the former).

def track_description_list(head):
    """Convert a TrackDescription linked list to a Python list (and release the former).
    """
    r = []
    if head:
        item = head
        while item:
            item = item.contents
            r.append((item.id, item.name))
            item = item.next
        try:
            libvlc_track_description_release(head)
        except NameError:
            libvlc_track_description_list_release(head)

    return r