openssl: Fix compilation without deprecated OpenSSL 1.1 APIs

openssl: Fix compilation without deprecated OpenSSL 1.1 APIs

EVP_CIPHER_CTX_init and _cleanup were deprecated in 1.1 and both were
replaced with _reset.

EVP_CIPHER_CTX_free in OpenSSL 1.1 replaces the cleanup/free combo of
earlier OpenSSL version. And OpenSSL 1.0.2 already calls cleanup as part
of _free.

Therefore we can remove the _cleanup calls and use the OpenSSL 1.1. API
everywhere.

Also removed initialisation with OpenSSL 1.1 as it is no longer
needed and causes compilation errors when disabling deprecated APIs.

Same with SSL_CTX_set_ecdh_auto as it got removed.

Patch V3: Use EVP_CIPHER_CTX_reset instead of init/cleanup

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Rosen Penev <rosenp@gmail.com>
Acked-by: Steffan Karger <steffan.karger@fox-it.com>
Message-Id: <20190724152934.9884-1-arne@rfc2549.org>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg18700.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit 8a01147ff77e4ae2e377744b89fbe4b6841b2bb0)