OpenSSL: SSLeay symbols are no longer available in OpenSSL 1.1

OpenSSL: SSLeay symbols are no longer available in OpenSSL 1.1

The old symbols do not exist anymore but the library gained new
equivalent symbols (OSSL). Use them instead of the old ones

Signed-off-by: Emmanuel Deloget <logout@free.fr>
Acked-by: Steffan Karger <steffan.karger@fox-it.com>
Message-Id: <9ce17efda7b1ed100e73554b1916c0bfa687d9d1.1487368114.git.logout@free.fr>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg14089.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>