check_pgsql: Leave 'min' value in query perfdata empty.

There is no reasonable default value for that.

plugins/check_pgsql.c

@@ -634,7 +634,7 @@ do_query (PGconn *conn, char *query)
 						? _("CRITICAL")
 						: _("UNKNOWN"));
 	printf (_("'%s' returned %f"), query, value);
-	printf ("|query=%f;%s;%s;0\n", value,
+	printf ("|query=%f;%s;%s;;\n", value,
 			query_warning ? query_warning : "",
 			query_critical ? query_critical : "");
 	return my_status;