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/X11/winX.c

@@ -117,7 +117,7 @@ struct window_procs X11_procs = {
     X11_putstr, genl_putmixed, X11_display_file, X11_start_menu, X11_add_menu,
     X11_end_menu, X11_select_menu,
     genl_message_menu, /* no need for X-specific handling */
-    X11_update_inventory, X11_mark_synch, X11_wait_synch,
+    X11_mark_synch, X11_wait_synch,
 #ifdef CLIPPING
     X11_cliparound,
 #endif
@@ -141,6 +141,8 @@ struct window_procs X11_procs = {
     X11_status_init, X11_status_finish, X11_status_enablefield,
     X11_status_update,
     genl_can_suspend_no, /* XXX may not always be correct */
+    X11_update_inventory,
+    X11_update_invent_slot,
 };
 
 /*
@@ -1270,6 +1272,17 @@ X11_update_inventory(int arg)
     return;
 }
 
+perminvent_info *
+X11_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;
+}
+
 /* The current implementation has all of the saved lines on the screen. */
 int
 X11_doprev_message(void)