Pull in latest networking dependencies

This updates maghemite, dendrite, and OPTE for the run-up to the IPv6
integration and attached subnet work. It does not actually use any new
functionality, but makes a few small API changes required for the OPTE
update.

Author: bnaecker

.github/buildomat/jobs/deploy.sh

@@ -2,7 +2,7 @@
 #:
 #: name = "helios / deploy"
 #: variety = "basic"
-#: target = "lab-2.0-opte-0.38"
+#: target = "lab-2.0-opte-0.39"
 #: output_rules = [
 #:  "%/var/svc/log/oxide-*.log*",
 #:  "%/zone/oxz_*/root/var/svc/log/oxide-*.log*",