Backport commit 06d716147 from Emacs

Fix some no-X build warnings
06d7161476255c77defa119fffa842b7abaa0dcb
Lars Ingebrigtsen
Mon Aug 22 19:22:33 2022 +0200

lisp/org-plot.el

@@ -621,7 +621,8 @@ manner suitable for prepending to a user-specified script."
   "Find any overlays for IMG-FILE in the current Org buffer, and refresh them."
   (dolist (img-overlay org-inline-image-overlays)
     (when (string= img-file (plist-get (cdr (overlay-get img-overlay 'display)) :file))
-      (when (file-exists-p img-file)
+      (when (and (file-exists-p img-file)
+                 (fboundp 'image-flush))
         (image-flush (overlay-get img-overlay 'display))))))
 
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