Check SSL_set1_chain error in set_cert_cb

CLA: trivial

Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from openssl#14469)

apps/lib/s_cb.c

@@ -952,7 +952,8 @@ static int set_cert_cb(SSL *ssl, void *arg)
                 if (!SSL_build_cert_chain(ssl, 0))
                     return 0;
             } else if (exc->chain != NULL) {
-                SSL_set1_chain(ssl, exc->chain);
+                if (!SSL_set1_chain(ssl, exc->chain))
+                    return 0;
             }
         }
         exc = exc->prev;