This reverts commit 061422affcc4278d0400c248432f39ee60fcf16e.
We have a way to support IPv6 on FreeBSD now.
Signed-off-by: Denton Gentry <dgentry@tailscale.com>
FreeBSD tun devices don't work with the way we implement IPv6
https://github.com/tailscale/tailscale/issues/1307
At least for now, remove any IPv6 addresses from the netmap.
Signed-off-by: Denton Gentry <dgentry@tailscale.com>