The PAM plugin lastlog, previously used (optional) by Netopeer2 and
Rousette, does not rotate /var/log/lastlog, and since we don't have
cron and logrotate this can potentially fill up /var.
This patch disables pam_lastlog.so from the build and drops the two
matching session lines for both Netopeer2 and Rousette. Both still
log user access to sysrepo, so no critical functionality is lost.
Follow-up to issue #542
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>