patch 9.0.0965: using one window for executing autocommands is insufficient

Problem:    Using one window for executing autocommands is insufficient.
Solution:   Use up to five windows for executing autocommands.
diff --git a/src/evalwindow.c b/src/evalwindow.c
index 3578669..f8c0c7a 100644
--- a/src/evalwindow.c
+++ b/src/evalwindow.c
@@ -1064,7 +1064,7 @@
 	    return;
 	}
     }
-    if (wp == aucmd_win)
+    if (is_aucmd_win(wp))
 	rettv->vval.v_string = vim_strsave((char_u *)"autocmd");
 #if defined(FEAT_QUICKFIX)
     else if (wp->w_p_pvw)