Don't use file notification on non-file buffers
Allow non-file buffers to declare that notification on their default-directory is sufficient to know when auto-revert updates are required by setting the new variable `buffer-auto-revert-by-notification' to non-nil. If nil, the default, then auto-revert will poll those buffers instead. (bug#35418). Currently, only Dired sets that variable. * lisp/autorevert.el (auto-revert-buffers): Modify condition for using notification. * lisp/files.el (buffer-auto-revert-by-notification): New variable. * lisp/dired.el (dired-mode): Set buffer-auto-revert-by-notification. * doc/emacs/arevert-xtra.texi (Non-File Buffers): Document new variable. * etc/NEWS (Changes in Specialized Modes and Packages): Describe new variable.