Fix 'set-window-configuration' and 'window-state-put'

Fix 'set-window-configuration' and 'window-state-put'

Fix some bugs with 'window-state-put' (Bug#69093).  Add new
hook 'window-kept-windows-functions' (Bug#68235).

* doc/lispref/windows.texi (Window Configurations): Mention
'window-kept-windows-functions'.
(Window Hooks): Describe new abnormal hook
'window-kept-windows-functions'.
* src/marker.c (Fmarker_last_position): New function to return
the last position of a marker even if its buffer is now dead.
* src/window.c (Fset_window_configuration): If
'window-kept-windows-functions' is non-nil, do not delete any
window whose buffer is now dead but remember all such windows in
a list to pass to 'window-kept-windows-functions'.  Run
'window-kept-windows-functions' if it is non-nil.
(Vwindow_kept_windows_functions): New abnormal hook run by
Fset_window_configuration and 'window-state-put' with two
arguments - the frame whose configuration is restored and a list
of entries for each window whose buffer was found dead during
restoration.  Each entry is a list of four elements, the window,
the dead buffer, and the last know positions of the start and
point of that window.
* lisp/window.el (window-state-put-kept-windows)
(window-state-put-selected-window): New variables.
(window--state-put-2): Make sure buffer is live before restoring
its state.  Set 'window-state-put-selected-window' to state's
selected window.  If 'window-kept-windows-functions' is non-nil,
do not delete any windows whose buffer is found dead but
remember all such windows in a list to pass to
'window-kept-windows-functions'.
(window-state-put): Run 'window-kept-windows-functions' if it is
non-nil.  Select window recorded in
'window-state-put-selected-window'.