Log the negotiated (NCP) cipher

Log the negotiated (NCP) cipher

To make it clear that NCP is in effect, print a log message (at --verb 2)
to show that we selected a cipher using NCP.

Signed-off-by: Steffan Karger <steffan.karger@fox-it.com>
Acked-by: Arne Schwabe <arne@rfc2549.org>
Message-Id: <1494859435-16379-1-git-send-email-steffan.karger@fox-it.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg14656.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit d4071dd1553ea5a70ab03659c623ff2ceeefaf9e)