Backport commit d5f6ff99c from Emacs

* lisp/org.el (image-refresh):
* lisp/ox-odt.el (clear-image-cache, image-size): Declare.

Quieten without-x org compilation
d5f6ff99c2b594919931b277a2d94d3a289ca764
Glenn Morris
Wed Feb 28 16:55:41 2018 -0500

lisp/org.el

@@ -18728,6 +18728,9 @@ INCLUDE-LINKED is passed to `org-display-inline-images'."
     (org-toggle-inline-images)
     (org-toggle-inline-images)))
 
+;; For without-x builds.
+(declare-function image-refresh "image" (spec &optional frame))
+
 (defun org-display-inline-images (&optional include-linked refresh beg end)
   "Display inline images.
 

lisp/ox-odt.el

@@ -2194,6 +2194,10 @@ SHORT-CAPTION are strings."
     (org-odt-create-manifest-file-entry media-type target-file)
     target-file))
 
+;; For --without-x builds.
+(declare-function clear-image-cache "image.c" (&optional filter))
+(declare-function image-size "image.c" (spec &optional pixels frame))
+
 (defun org-odt--image-size
   (file info &optional user-width user-height scale dpi embed-as)
   (let* ((--pixels-to-cms