window port interface change - add mbehavior flags to start_menu()

Provide a way to communicate additional behaviors and/or appearances
desired from NetHack window port menus.

This is foundation work for changes to follow at a future date.

src/pager.c

@@ -1232,7 +1232,7 @@ coord *click_cc;
 
             any = cg.zeroany;
             win = create_nhwindow(NHW_MENU);
-            start_menu(win);
+            start_menu(win, MENU_BEHAVE_STANDARD);
             any.a_char = '/';
             /* 'y' and 'n' to keep backwards compatibility with previous
                versions: "Specify unknown object by cursor?" */
@@ -2111,7 +2111,7 @@ dohelp()
     int sel;
 
     any = cg.zeroany; /* zero all bits */
-    start_menu(tmpwin);
+    start_menu(tmpwin, MENU_BEHAVE_STANDARD);
 
     for (i = 0; help_menu_items[i].text; i++) {
         if (!wizard && help_menu_items[i].f == dispfile_debughelp)