Log Message:
Update sysutils/logroate to 3.16.0.

Upstream changelog:
* fix compilation with gcc-10, which defaults to -fno-common (#288)
* reduce number of open() operations on state file (#282)
* validate user/group given to the su directive early (#276)
* add hardening options to systemd unit file in examples (#274, #291)
* fix crash of logrotate on invalid configuration with include (#271)
* fix heap buffer overflow on too long logfile extension (#270)

Pkgsrc changes:
* a systemd example service file is added to the examples;
* a btmp and wtmp example configurations files are also added, but only
btmp is copied alongside logrotate.conf: while the 2 config files were at first
present in logrotate.conf, only btmp is present on NetBSD ;
* the GITHUB_RELEASE variable is moved for pkglint compliance.