Mark 13.4-RELEASE, 14.1-RELEASE, and 15.0-CURRENT verified.

Add MBP / BCM43602 to the list of working configurations.

Reported by:	Joshua Rogers <Joshua@Joshua.Hu>

Mark 13.3-RELEASE, 14.0-RELEASE, and 15.0-CURRENT verified.

Include information about IPv6 configuration on the manual page.

Note that this only has effect if the guest supports that and it
is enabled there.

Bump FreeBSD 12 to 12.4-RELEASE.

Update test configuration data.

Update test configuration data.

Improve comments for the guest-related sample configuration files.

Add hints on how to block loading native device drivers.

Fix creation of `/var/lock`.

This directory will be fixed on the first launch of the guest, so
it is better to create it right away.  It aids proper management
of package files.