OpenSSL: don't use direct access to the internal of X509_STORE_CTX

OpenSSL: don't use direct access to the internal of X509_STORE_CTX

OpenSSL 1.1 does not allow us to directly access the internal of
any data type, including X509_STORE_CTX. We have to use the defined
functions to do so.

Fortunately, these functions have existed since the dawn of time so
we don't have any compatibility issue here.

Signed-off-by: Emmanuel Deloget <logout@free.fr>
Acked-by: Steffan Karger <steffan.karger@fox-it.com>
Message-Id: <11477a0a3cf636572c84e0110a6f1b726bc60c2c.1487368114.git.logout@free.fr>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg14085.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>