emacspeak: Use bundled espeak server instead of espeak-ng

Emacspeak comes with its own native speech server which is compiled in
the derivation but never actually used by emacspeak. Instead emacspeak
uses espeak-ng, which echoes every command issued to the server and
won't shut up about tts sync states.

Fix this by setting DTK_PROGRAM to the bundled espeak server.

pkgs/applications/editors/emacs/elisp-packages/emacspeak/default.nix

@@ -45,7 +45,8 @@ stdenv.mkDerivation rec {
     find "$d" \( -type d -or \( -type f -executable \) \) -execdir chmod 755 {} +
     find "$d" -type f -not -executable -execdir chmod 644 {} +
     makeWrapper ${emacs}/bin/emacs $out/bin/emacspeak \
-        --set DTK_PROGRAM "${espeak-ng}/bin/espeak" \
+        --set DTK_PROGRAM "${placeholder "out"}/share/emacs/site-lisp/emacspeak/servers/espeak" \
+        --set TCLLIBPATH "${tclx}/lib" \
         --add-flags '-l "${placeholder "out"}/share/emacs/site-lisp/emacspeak/lisp/emacspeak-setup.elc"'
   '';