Timer: play a sound as configured by `org-clock-sound' actualy only beep

* lisp/org-timer.el (org-timer-set-timer): Use the variable
  `org-clock-sound' when calling `org-notify'.

When org-notify second parameter is t we only get the standard beep.
Evaluating with coma we can use different sounds for differents
running timers, as `org-clock-sound' was set when
`org-timer-set-timer' get execute

Patch proposal by Roberto Huelga Díaz.

TINYCHANGE

lisp/org-timer.el

@@ -429,7 +429,7 @@ replace any running timer."
 		    (run-with-timer
 		     secs nil `(lambda ()
 				 (setq org-timer-current-timer nil)
-				 (org-notify ,(format "%s: time out" hl) t)
+				 (org-notify ,(format "%s: time out" hl) ,org-clock-sound)
 				 (setq org-timer-timer-is-countdown nil)
 				 (org-timer-set-mode-line 'off)
 				 (run-hooks 'org-timer-done-hook))))