groundwork for an interface change

Add a new window-port interface function
     perminvent_info *
     update_invent_slot(winid window, int slot, perminvent_info *);

That should be nice and flexible and allow exchanges of useful
information between the core and the window port. Information
to be exchange can be easily modified in include/wintype.h as
things evolve.

Information useful to the core can be exchanged from the
window-port in struct to_core.

Information useful from the core to the window-port can be
passed in struct from_core.

I'm not going to update any docs until much later after things
are fully working and settled.

This also doesn't fix or have anything to do with existing
TTY_PERM_INVENT issues.

win/tty/wintty.c

@@ -135,7 +135,7 @@ struct window_procs tty_procs = {
     tty_destroy_nhwindow, tty_curs, tty_putstr,
     tty_putmixed,
     tty_display_file, tty_start_menu, tty_add_menu, tty_end_menu,
-    tty_select_menu, tty_message_menu, tty_update_inventory, tty_mark_synch,
+    tty_select_menu, tty_message_menu, tty_mark_synch,
     tty_wait_synch,
 #ifdef CLIPPING
     tty_cliparound,
@@ -166,6 +166,8 @@ struct window_procs tty_procs = {
     genl_status_update,
 #endif
     genl_can_suspend_yes,
+    tty_update_inventory,
+    tty_update_invent_slot,
 };
 
 winid BASE_WINDOW;
@@ -3597,6 +3599,17 @@ tty_update_inventory(int arg UNUSED)
     return;
 }
 
+perminvent_info *
+tty_update_invent_slot(
+    winid window UNUSED,  /* window to use, must be of type NHW_MENU */
+    int inventory_slot UNUSED,          /* slot id: 0 - info return to core */
+                                        /*          1 - gold slot */
+                                        /*          2 - 29 obj slots */
+    perminvent_info *pi UNUSED)
+{
+    return (perminvent_info *) 0;
+}
+
 #ifdef TTY_PERM_INVENT
 
 /* put the formatted object description for one item into a particular row