options: make 'tun' the default for '--dev'

options: make 'tun' the default for '--dev'

With this change, OpenVPN can be launched without specifying
any --dev option and it will start a `tun` (L3) tunnel with the
interface named `tunX`.
As before, this behaviour can be changed using --dev or --dev-type.

Existing configs won't see any behavioural change as they all
had to contain at least one --dev directive.

Change-Id: I0ca7b5b7ec1a01acaad222c99db137c94c88555a
Signed-off-by: Antonio Quartulli <antonio@mandelbit.com>
Acked-by: Frank Lichtenheld <frank@lichtenheld.com>
Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1537
Message-Id: <20260724055529.1376-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg37825.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>