custom version of ibuffer-auto-hook to use simpler local post-command-hook rather than global

my-ibuffer-auto.el

(defun my-ibuffer-auto-update-changed ()
  (when (frame-or-buffer-changed-p 'ibuffer-auto-buffers-changed)
    (ibuffer-update nil t)))

(defun my-ibuffer-auto-mode ()
  (frame-or-buffer-changed-p 'ibuffer-auto-buffers-changed) ; initialize
  (add-hook 'post-command-hook 'my-ibuffer-auto-update-changed nil t))

(add-hook 'ibuffer-mode-hook 'my-ibuffer-auto-mode)