net-mgmt/lldpd: Update to 1.0.18

• Use writable chroot for timezone file
• USES=pkgconfig to detect system libevent
• Remove obsolete (since 0.9.7) JSON option
• Remove unnecessary USES=libedit with XML option
• Pet portlint and other minor improvements

Changelogs:

• https://github.com/lldpd/lldpd/releases/tag/1.0.15
• https://github.com/lldpd/lldpd/releases/tag/1.0.16
• https://github.com/lldpd/lldpd/releases/tag/1.0.17
• https://github.com/lldpd/lldpd/releases/tag/1.0.18

PR: 277851
Reported by: ngie
Reviewed by: ngie
Approved by: maintainer timeout (three months)
Sponsored by: Saltant Solutions LLC
Differential Revision: https://reviews.freebsd.org/D45168