There is no need to rotate /var/log/lastlog, this file is not growing in size.

Please add a comment in its man page, like in debian about this issue.

NOTE
       The lastlog file is a database which contains info on the last login of
       each user. You should not rotate it. It is a sparse file, so its size
       on the disk is usually much smaller than the one shown by "ls -l"
       (which can indicate a really big file if you have in passwd users with
       a high UID). You can display its real size with "ls -s".


Thanks.

This note is already in man page, added by upstream.