security/zeek: Update to 5.0.0 (latest LTS release)

https://github.com/zeek/zeek/releases/tag/v5.0.0

Changes incompatiable with 4.0.7:

• The script-land `union and timer` types have been removed. They haven't had any actual semantics backing them for some time and shouldn't have functioned in any useable way. We opted to skip the deprecation cycle for these types for that reason.
• Broker now uses a new network backend with a custom network protocol that is incompatible with the pre-5.0 backend. In practice, this means Zeek 4.x will not be able to exchange events with Zeek 5.x. Going forward, this new backend will allow us to keep the Broker protocol more stable and add new capabilities in a backwards compatible way.

While we're here add a comment explaining why we really need uname
-p instead of using ARCH (uname -m). Also solve a portlint nag.

Reported by: Tim Wojtulewicz