maddr: export VLAN ID from client context to maddr object

maddr: export VLAN ID from client context to maddr object

When receiving a packet from a client, the associated maddr needs to
carry also the VID associated with that client. This way the VID can be
appended to the packet later, if needed.

This patch adds support for exporting the VID from the client context to
the related per-packet maddr object.

Signed-off-by: Fabian Knittel <fabian.knittel@lettink.de>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20191009143422.9419-4-a@unstable.cc>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg18917.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>