bug#9867: 24.0.90; quit-window should provide quit-window-hook

[martin rudalics <rudalics@gmx.at>]

 > It seems like Chong OK'd this hook at the time, but it was never added
 > to Emacs.  I've now added it to Emacs 27, because it seems like a useful
 > addition to have -- now modes that need to do some clean-up thing before
 > doing whatever `quit-window' does can just add that to the hook
 > (buffer-locally).

'quit-restore-window' can quit _any_ window not just the selected one.
This means that if a user puts something on a normal hook run by that
function, that something can only guess at which window is really quit
by that function.  Also, running a buffer-local value of that hook is
meaningless given the current implementation.  See the tribulations
run_window_configuration_change_hook runs into when trying to overcome
a similar problem (and note the unwind-protection overhead it incurs).

If people really need such a hook at all, please

- Make it either an abnormal hook run with the window quit as argument
   or run it from 'quit-window' but then only if it quits the selected
   window.

- Make sure to call any buffer-local value of that hook for the buffer
   of the window that is quit.

- Prefix it with 'quit-restore-' if you intend to run it from
   'quit-restore-window' (that function may be called by other
   functions as well).

- Fix the reference to the non-existent function 'quit-buffer'.

Thanks, martin