Fix compile error in ssl_openssl introduced by polar external-management patch

Acked-by: Steffan Karger <steffan@karger.me>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1385210434-28364-1-git-send-email-arne@rfc2549.org>
URL: http://article.gmane.org/gmane.network.openvpn.devel/8039

Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit 20fe5561dfe7a6f1da3aac07b38d0773c2758e5e)