remove slipped-in partial bits from another feature

Some bits from another feature by Tangles had
slipped into our merge of curses a while back.

Remove the partial bits as feature bits should
be complete or not at all, unless foundational
for something to come.

include/flag.h

@@ -369,8 +369,6 @@ struct instance_flags {
     boolean wizweight;       /* display weight of everything in wizard mode */
     boolean cmdassist;       /* provide detailed assistance for some commands */
     boolean clicklook;          /* allow right-clicking for look */
-    boolean msg_is_alert;    /* suggest windowport should grab player's attention
-                              * and request <TAB> acknowlegement */
     int statuslines;         /* default = 2, code support for alternative 3 */
     /*
      * Window capability support.

win/curses/cursmesg.c

@@ -148,18 +148,13 @@ curses_block(boolean noscroll)
 
     curses_get_window_size(MESSAGE_WIN, &height, &width);
     curses_toggle_color_attr(win, MORECOLOR, NONE, ON);
-    mvwprintw(win, my, mx, iflags.msg_is_alert ? "<TAB!>" : ">>");
+    mvwprintw(win, my, mx, ">>");
     curses_toggle_color_attr(win, MORECOLOR, NONE, OFF);
-    if (iflags.msg_is_alert)
-        curses_alert_main_borders(TRUE);
     wrefresh(win);
-    while (iflags.msg_is_alert && (ret = wgetch(win) != '\t'));
     /* msgtype=stop should require space/enter rather than
      * just any key, as we want to prevent YASD from
      * riding direction keys. */
-    while (!iflags.msg_is_alert && (ret = wgetch(win)) && !index(resp,(char)ret));
+    while ((ret = wgetch(win)) && !index(resp,(char)ret));
-    if (iflags.msg_is_alert)
-        curses_alert_main_borders(FALSE);
     if (height == 1) {
         curses_clear_unhighlight_message_window();
     } else {