remove text noise created by stock openssl

lib.d/make-selfsigned-wildcard-ssl-cert.sh

@@ -129,7 +129,7 @@ $OPENSSL req \
 
 rm $ssl_config
 
-if $OPENSSL x509 -in $certfile -noout -text | grep -i signature | grep -vi sha256 ; then
+if $OPENSSL x509 -in $certfile -noout -text | grep -i signature | grep -vi sha256 >/dev/null ; then
     (
         echo $this: WARNING: the cert is not signed with SHA256
         echo $this: this is not fatal, but worth checking