terminal.c: need maketitle() in terminal-mode

normal_redraw() usually takes care of this, but that doesn't happen
during terminal-mode.

regression by c484323dc6
steps to reproduce:
    nvim -u NORC --cmd 'execute("set titlestring=" . $NVIM_LISTEN_ADDRESS) | set title | startinsert | !sleep 1' term://sh

closes #7248

src/nvim/screen.c

@@ -5847,7 +5847,7 @@ static void screen_start_highlight(int attr)
   ui_start_highlight(attr);
 }
 
-void screen_stop_highlight(void)
+static void screen_stop_highlight(void)
 {
   ui_stop_highlight();
   screen_attr = 0;