groundwork for window port interface change to add_menu

groundwork only - window port interface change

This changes the last parameter for add_menu() from a boolean
to an unsigned int, to allow additional itemflags in future
beyond just the "preselected" that the original boolean offered.

There shouldn't be any functionality changes with this groundwork-only
change, and if there are it is unintentional and should be reported.

src/nhlua.c

@@ -482,7 +482,8 @@ lua_State *L;
         if (*key)
             any.a_char = key[0];
         add_menu(tmpwin, NO_GLYPH, &any, 0, 0, ATR_NONE, str,
-                 (*defval && *key && defval[0] == key[0]) ? MENU_SELECTED : MENU_UNSELECTED);
+                 (*defval && *key && defval[0] == key[0])
+                    ? MENU_ITEMFLAGS_SELECTED : MENU_ITEMFLAGS_NONE);
 
         lua_pop(L, 1); /* removes 'value'; keeps 'key' for next iteration */
     }