openssl: don't use deprecated SSLEAY/SSLeay symbols

openssl: don't use deprecated SSLEAY/SSLeay symbols

Compiling our current master against OpenSSL 1.1 with
-DOPENSSL_API_COMPAT=0x10100000L screams bloody murder.  This patch fixes
the errors about the deprecated SSLEAY/SSLeay symbols and defines.

Signed-off-by: Steffan Karger <steffan@karger.me>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20171126150401.28565-1-steffan@karger.me>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg15934.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>