Fix spelling not working in speech output

The problem with spelling is that SSIP doesn't allow setting it inside blocks.
speechd-out-text always wraps the text and a contingent attached icon by an
outer block, which effectively prohibits spelling (and other parameters not
allowed in SSIP blocks) from being set.

Let's use the outer block only if there is an icon.  This is not a complete fix,
texts with attached icons still aren't spelled, but it's the easiest fix for
now.  A complete fix would be much more complicated.

speechd-out.el

@@ -1,6 +1,6 @@
 ;;; speechd-out.el --- Alternative output interface  -*- lexical-binding: t -*-
 
-;; Copyright (C) 2018-2021 Milan Zamazal <pdm@zamazal.org>
+;; Copyright (C) 2018-2024 Milan Zamazal <pdm@zamazal.org>
 ;; Copyright (C) 2004, 2005, 2006, 2008 Brailcom, o.p.s.
 
 ;; Author: Milan Zamazal <pdm@brailcom.org>
@@ -207,10 +207,13 @@
             (text% text)
             (cursor% cursor)
             (markers% markers))
-        (speechd.block driver (lambda ()
-                                (when icon-name%
-                                  (speechd.icon driver% icon-name%))
-                                (speechd.text driver% text% cursor% markers%)))))))
+        ;; Some parameters, e.g. spelling, cannot be set inside blocks;
+        ;; use a block only if necessary.
+        (if icon-name%
+            (speechd.block driver (lambda ()
+                                    (speechd.icon driver% icon-name%)
+                                    (speechd.text driver% text% cursor% markers%)))
+          (speechd.text driver% text% cursor% markers%))))))
 
 (defun speechd-out-set (parameter value)
   (speechd-out--loop-drivers (driver)