Deprecate `org-format-seconds' in favor of `format-seconds'

* lisp/org-macs.el (org-format-seconds): Remove function.
* lisp/org-compat.el (org-format-seconds): Mark function as an obsolete
  alias.
* lisp/org-table.el (org-table-time-seconds-to-string):
* lisp/ox.el (org-export-stack-refresh): Apply removal.

lisp/org-compat.el

@@ -94,6 +94,7 @@
 (define-obsolete-function-alias 'org-called-interactively-p 'called-interactively-p "Org 9.0")
 (define-obsolete-function-alias 'org-char-to-string 'char-to-string "Org 9.0")
 (define-obsolete-function-alias 'org-delete-directory 'delete-directory "Org 9.0")
+(define-obsolete-function-alias 'org-format-seconds 'format-seconds "Org 9.0")
 (define-obsolete-function-alias 'org-no-warnings 'with-no-warnings "Org 9.0")
 (define-obsolete-function-alias 'org-number-sequence 'number-sequence "Org 9.0")
 (define-obsolete-function-alias 'org-pop-to-buffer-same-window 'pop-to-buffer-same-window "Org 9.0")

lisp/org-macs.el

@@ -284,12 +284,6 @@ The number of levels is controlled by `org-inlinetask-min-level'"
 			  limit-level)))
 	   (format "\\*\\{1,%d\\} " nstars)))))
 
-(defun org-format-seconds (string seconds)
-  "Compatibility function replacing format-seconds."
-  (if (fboundp 'format-seconds)
-      (format-seconds string seconds)
-    (format-time-string string (seconds-to-time seconds))))
-
 (defmacro org-eval-in-environment (environment form)
   (declare (debug (form form)) (indent 1))
   `(eval (list 'let ,environment ',form)))

lisp/org-table.el

@@ -3728,7 +3728,7 @@ minutes or seconds."
 		 (format "%.1f" (/ (float secs0) 60)))
 		((eq output-format 'seconds)
 		 (format "%d" secs0))
-		(t (org-format-seconds "%.2h:%.2m:%.2s" secs0)))))
+		(t (format-seconds "%.2h:%.2m:%.2s" secs0)))))
     (if (< secs 0) (concat "-" res) res)))
 
 (defun org-table-fedit-convert-buffer (function)

lisp/ox.el

@@ -6137,9 +6137,8 @@ stack."
 		    (let ((data (nth 2 entry)))
 		      (if proc-p (format " %6s  " (process-status data))
 			;; Compute age of the results.
-			(org-format-seconds
-			 "%4h:%.2m  "
-			 (float-time (time-since data)))))
+			(format-seconds "%4h:%.2m  "
+					(float-time (time-since data)))))
 		    ;; Source.
 		    (format " %s"
 			    (let ((source (car entry)))