patch 9.1.0931: ml_get error in terminal buffer

Problem:  ml_get error in terminal buffer (user202729)
Solution: call update_topline() in win_enter_ext() for terminal buffers
          (h-east)

fixes: #16024
closes: #16211

Signed-off-by: h-east <h.east.727@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/window.c

@@ -5578,6 +5578,10 @@ win_enter_ext(win_T *wp, int flags)
 	did_decrement = TRUE;
     }
 #endif
+#ifdef FEAT_TERMINAL
+    if (bt_terminal(curwin->w_buffer))
+	update_topline();
+#endif
 
     win_fix_current_dir();