* autorevert.el (top): Require 'cl in order to pacify byte compiler.

* autorevert.el (top): Require 'cl in order to pacify byte compiler.
(auto-revert-notify-rm-watch): Ignore errors.
(auto-revert-notify-add-watch): Ignore errors.  Use '(modify) for
inotify, and '(size last-write-time) for w32notify.  Set
buffer-local `auto-revert-use-notify' to nil when adding a file
watch fails - this is a fallback to the file modification check.
(auto-revert-notify-event-p, auto-revert-notify-event-descriptor)
(auto-revert-notify-event-action)
(auto-revert-notify-event-file-name): New defuns.
(auto-revert-notify-handler): Use them.  Implement first
plausibility checks.
(auto-revert-handler): Handle also `auto-revert-tail-mode'.