patch 8.2.4739: accessing freed memory after WinScrolled autocmd event

Problem:    Accessing freed memory after WinScrolled autocmd event.
Solution:   Check the window pointer is still valid. (closes #10156)
            Remove the argument from may_trigger_winscrolled().
diff --git a/src/proto/window.pro b/src/proto/window.pro
index 589dd09..9625942 100644
--- a/src/proto/window.pro
+++ b/src/proto/window.pro
@@ -17,7 +17,7 @@
 void close_windows(buf_T *buf, int keep_curwin);
 int one_window(void);
 int win_close(win_T *win, int free_buf);
-void may_trigger_winscrolled(win_T *wp);
+void may_trigger_winscrolled(void);
 void win_close_othertab(win_T *win, int free_buf, tabpage_T *tp);
 void win_free_all(void);
 win_T *winframe_remove(win_T *win, int *dirp, tabpage_T *tp);