The device name "tailscale0" will be used for all platforms except for
OpenBSD where "tun" is enforced by the kernel. `CreateTUN()` in
`wireguard-go` will select the next available "tunX" device name on the
OpenBSD system.
Signed-off-by: Martin Baillie <martin@baillie.email>
The MTU is currently set when creating the tun device,
elsewhere in the code. Maybe someday we'll want some kind
of per-platform MTU configuration here, but not in the
short-medium term.
Signed-off-by: David Anderson <dave@natulte.net>
