Enable privelege separtion and minor fixes

[krion]

Summary

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=216737

• enables privilege separation
• removes the build dependency on asciidoctor
• removes the runtime dependency on makeinfo and readline
• add a runtime dependency on libedit
• do not install the HTML documentation (in favour of man pages)
• update the post-install message (pkg-message) in light of privilege separation
• set the permission of /var/db/chrony to the new "chronyd" user and group

[mat]

net/chrony/pkg-message

3

s/make deinstall/pkg delete chronyd/

net/chrony/pkg-plist

7–9

This should be:

@dir(chronyd,chronyd,) /var/db/chronyd

[krion]

Fix plist and pkg-message.