Deprecate --no-iv

Deprecate --no-iv

This fixes the bug of supporting --no-iv (since we're only accepting
bugfixes in the current release phase ;) ).

The --no-iv function decreases security if used (CBC *requires*
unpredictable IVs, other modes don't allow --no-iv at all), and even
marginally decreases other user's security by adding unwanted
complexity to our code.

Let's get rid of this.

Signed-off-by: Steffan Karger <steffan@karger.me>
Acked-by: Gert Doering <gert@greenie.muc.de>
Acked-by: Arne Schwabe <arne@rfc2549.org>
Message-Id: <1481138447-6292-1-git-send-email-steffan@karger.me>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg13430.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>