Rather than relying on the sysctl net.link.tap.up_on_open automatically
try to IFF_UP the opened tap device.
When moving installations a lot in devleopment environments forgetting
to set the sysctl is annoying and having to in first place too.
If you want communications with the outside world and tell bhyve to
create an interfaces then it should be usable as well.
MFC after: 10 days