Remove IV_RGI6=1 peer-info signalling.

Remove IV_RGI6=1 peer-info signalling.

This is no longer needed, as anything 2.4 or later is known to have
this functionality, and IV_VER can be used to detect this on the server.

Signed-off-by: Gert Doering <gert@greenie.muc.de>
Acked-by: Steffan Karger <steffan@karger.me>
Acked-by: David Sommerseth <davids@openvpn.net>
Message-Id: <20161225105919.25792-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg13706.html
Signed-off-by: David Sommerseth <davids@openvpn.net>
(cherry picked from commit 392c9e47f6418612bc2a4932faf22bb711e65a54)