OpenSSL: Always set SSL_OP_CIPHER_SERVER_PREFERENCE flag

OpenSSL: Always set SSL_OP_CIPHER_SERVER_PREFERENCE flag

* safe bet to say that server admins are better at updating their configs
  than client users are and if client do want to restrict their ciphers,
  they should simply evict the ciphers they don't want from their cipher
  suite
* mbed TLS and OpenSSL behave more similar with the
  SSL_OP_CIPHER_SERVER_PREFERENCE flag

Signed-off-by: Szilárd Pfeiffer <coroner@pfeifferszilard.hu>
Acked-by: Steffan Karger <steffan.karger@fox-it.com>
Message-Id: <20170904081012.1975-1-coroner@pfeifferszilard.hu>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg15356.html
Signed-off-by: David Sommerseth <davids@openvpn.net>
(cherry picked from commit 5fd8e94d311825571931414064e4d13ed808f9b5)