Fix a few more warnings in small configurations
diff --git a/programs/x509/cert_app.c b/programs/x509/cert_app.c
index 6b03266..30906b1 100644
--- a/programs/x509/cert_app.c
+++ b/programs/x509/cert_app.c
@@ -406,7 +406,9 @@
 
         ssl_set_own_cert( &ssl, &clicert, &pkey );
 
+#if defined(POLARSSL_SSL_SERVER_NAME_INDICATION)
         ssl_set_hostname( &ssl, opt.server_name );
+#endif
 
         /*
          * 4. Handshake