Accommodate Emacs 26

If `window-buffer-change-functions` isn't bound fallback
to `bookmark-after-jump-hook`.

The window argument for the inserted hook is optional to
accommodate both cases.

lisp/pdf-view.el

@@ -1663,11 +1663,15 @@ See also `pdf-view-bookmark-make-record'."
          (file (bookmark-prop-get bmk 'filename))
          (buf (or (find-buffer-visiting file)
                   (find-file-noselect file)))
+         (buf-chg-fns-p (boundp 'window-buffer-change-functions))
+         (hook (if buf-chg-fns-p
+                   'window-buffer-change-functions
+                 'bookmark-after-jump-hook))
          (show-fn-sym (make-symbol "pdf-show-buffer-function")))
     (fset show-fn-sym
-          (lambda (win)
-            (with-current-buffer buf
-              (remove-hook 'window-buffer-change-functions show-fn-sym t)
+          (lambda (&optional win)
+            (when (eq buf (current-buffer))
+              (remove-hook hook show-fn-sym buf-chg-fns-p)
               (unless (derived-mode-p 'pdf-view-mode)
                 (pdf-view-mode))
               (when size
@@ -1687,7 +1691,7 @@ See also `pdf-view-bookmark-make-record'."
                                  1
                                (frame-char-height))))))))))
     (set-buffer buf)
-    (add-hook 'window-buffer-change-functions show-fn-sym nil t)))
+    (add-hook hook show-fn-sym nil buf-chg-fns-p)))
 
 (defun pdf-view-bookmark-jump (bmk)
   "Switch to bookmark BMK.