Fix error in ssltest

Compiling ssltest with some compilers using --strict-warnings results in
complaints about an unused result.

Reviewed-by: Kurt Roeckx <kurt@openssl.org>
diff --git a/test/ssltest.c b/test/ssltest.c
index 71cc126..2ca4d69 100644
--- a/test/ssltest.c
+++ b/test/ssltest.c
@@ -1626,8 +1626,9 @@
         rv = SSL_CONF_cmd(c_cctx, arg, argn);
         /* If not recognised use server context */
         if (rv == -2) {
-            (void)SSL_CONF_cmd(s_cctx2, arg, argn);
-            rv = SSL_CONF_cmd(s_cctx, arg, argn);
+            rv = SSL_CONF_cmd(s_cctx2, arg, argn);
+            if (rv > 0)
+                rv = SSL_CONF_cmd(s_cctx, arg, argn);
         }
         if (rv <= 0) {
             BIO_printf(bio_err, "Error processing %s %s\n",