Remove ENABLE_BUFFER_LIST

it is unconditionally enabled and OpenVPN does not compile if disabled
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1404735142-31420-4-git-send-email-arne@rfc2549.org>
URL: http://article.gmane.org/gmane.network.openvpn.devel/8841

Signed-off-by: Gert Doering <gert@greenie.muc.de>