BUG/MINOR: ssl: fix SSL_CTX_set1_chain compatibility for openssl < 1.0.2

BUG/MINOR: ssl: fix SSL_CTX_set1_chain compatibility for openssl < 1.0.2

Commit 1c65fdd5 "MINOR: ssl: add extra chain compatibility" really implement
SSL_CTX_set0_chain. Since ckch can be used to init more than one ctx with
openssl < 1.0.2 (commit 89f58073 for X509_chain_up_ref compatibility),
SSL_CTX_set1_chain compatibility is required.

This patch must be backported to 2.1.

(cherry picked from commit 140b64fb562fb08cecf93ca6bec99822f7d556fb)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>