use ctrl_nhwindow() for menu prompt style

This implements the mechanics to use the ctrl_nhwindow() interface
capability to pass down a setting change from the core to the active
window port, without resorting to accessing a core global variable
from within the window port, and without altering the interface..

The passed setting is honored in the tty and curses window ports.

X11 and mswin receive and store the values, but no implementation
to change the menu prompt style is there yet.

Qt does not store the values or have an implementation.

The setting change is done in allmain.c immediately after
creating the WIN_INVEN window.

win/tty/wintty.c

@@ -2593,6 +2593,8 @@ reverse(tty_menu_item *curr)
     return head;
 }
 
+static color_attr tty_menu_promptstyle = { NO_COLOR, ATR_NONE };
+
 /*
  * End a menu in this window, window must a type NHW_MENU.  This routine
  * processes the string list.  We calculate the # of pages, then assign
@@ -2642,7 +2644,8 @@ tty_end_menu(
         tty_add_menu(window, &nul_glyphinfo, &any, 0, 0,
                      ATR_NONE, clr, "", MENU_ITEMFLAGS_NONE);
         tty_add_menu(window, &nul_glyphinfo, &any, 0, 0,
-                     ATR_NONE, clr, prompt, MENU_ITEMFLAGS_NONE);
+                     tty_menu_promptstyle.attr, tty_menu_promptstyle.color,
+                     prompt, MENU_ITEMFLAGS_NONE);
     }
 
     /* 52: 'a'..'z' and 'A'..'Z'; avoids selector duplication within a page */
@@ -2807,22 +2810,20 @@ RESTORE_WARNING_FORMAT_NONLITERAL
 win_request_info *
 tty_ctrl_nhwindow(winid window UNUSED, int request, win_request_info *wri)
 {
-#if !defined(TTY_PERM_INVENT)
-    wri = (win_request_info *) 0;
-    nhUse(window);
-    nhUse(request);
-#else
+#if defined(TTY_PERM_INVENT)
     boolean tty_ok /*, show_gold */, inuse_only;
     int maxslot;
     /* these types are set match the wintty.h field declarations */
     long minrow; /* long to match maxrow declaration in wintty.h */
     short offx, offy;
     long rows, cols, maxrow, maxcol;
+#endif
 
     if (!wri)
         return (win_request_info *) 0;
 
     switch (request) {
+#if defined(TTY_PERM_INVENT)
     case set_mode:
     case request_settings:
         ttyinvmode = wri->fromcore.invmode;
@@ -2850,11 +2851,14 @@ tty_ctrl_nhwindow(winid window UNUSED, int request, win_request_info *wri)
             wri->tocore.maxslot = maxslot;
         }
         break;
+#endif  /* TTY_PERM_INVENT */
+    case set_menu_promptstyle:
+        tty_menu_promptstyle = wri->fromcore.menu_promptstyle;
+        break;
     default:
         impossible("invalid request to tty_ctrl_nhwindow: %d", request);
         break;
     }
-#endif
     return wri;
 }