We can not have sysmocom-backup-default and sysmocom-backup-data-default
installed at the same time. I don't want to play games with RREPLACE and
RPROVIDES either. So simply use one of the two files. Copy the two more
default values over to the other recipe.
Move the default file list to a separate file in /etc/sysmocom/backup.d,
which is itself included in the backup. Also create a symlink to the
most recent backup.