nanobsd: Fix pkg audit

[senguptaangshuman17_gmail.com]

Summary

Create /conf/default/var/db/pkg in the skeleton so read only pkg
operations such as pkg audit find var/db/pkg at runtime.

[jlduran]

This revision should be squashed with D58951.
In fact, those revisions that start the commit message with: Fix... should be squashed accordingly to its root commit, unless they fix something already in base.

tools/tools/nanobsd/defaults.sh

1220

[senguptaangshuman17_gmail.com]

Squashed into D58951 (Support pkgbase in -P pre-compiled builds) during setup_nanobsd() pkg database directory initialization cleanup.