test/ssl_old_test.c: Do NULL pointer check before its use

In openssl-3.0.0 and system provided, it is not reasonable to
check null pointer after use. The order was accidentally reversed.
Therefore, it is better to correct it.

CLA: trivial

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16915)

test/ssl_old_test.c

diff --git a/test/ssl_old_test.c b/test/ssl_old_test.c
index 3ccc8e0..6a206d5 100644
--- a/test/ssl_old_test.c
+++ b/test/ssl_old_test.c
@@ -1896,9 +1896,9 @@
     BIO_snprintf(addr_str, sizeof(addr_str), ":%s", BIO_get_accept_port(acpt));
 
     client = BIO_new_connect(addr_str);
-    BIO_set_conn_ip_family(client, family);
     if (!client)
         goto err;
+    BIO_set_conn_ip_family(client, family);
 
     if (BIO_set_nbio(client, 1) <= 0)
         goto err;