messages: redraw tabline if it was overdrawn by messages

fixes #8354

Regression from #8088, where we try to avoid clearing the screen
if not absolutely necessary

src/nvim/screen.c

@@ -309,6 +309,9 @@ void update_screen(int type)
         if (wp->w_winrow + wp->w_height + wp->w_status_height > valid) {
           wp->w_redr_status = true;
         }
+        if (valid == 0) {
+          redraw_tabline = true;
+        }
       }
     } else if (msg_scrolled > Rows - 5) {  // clearing is faster
       type = CLEAR;