Backport commit 331ddd803 from Emacs

* lisp/org-macs.el (org--string-from-props): Pacify warnings
about unknown functions in non-GUI bilds.

Address some --without-x byte-compilation warnings
331ddd803a72056d0f0c70e5a677e0d4a6300584
Basil L. Contovounesios
Fri Mar 26 17:35:34 2021 +0000

lisp/org-macs.el

@@ -869,7 +869,8 @@ delimiting S."
 		    (let ((width (plist-get props :width)))
 		      (and (wholenump width) width)))
 		   (`(image . ,_)
-		    (ceiling (car (image-size spec))))
+                    (and (fboundp 'image-size)
+                         (ceiling (car (image-size spec)))))
 		   ((pred stringp)
 		    ;; Displayed string could contain invisible parts,
 		    ;; but no nested display.