patch 8.1.1425: win_execute() does not set window pointers properly

Problem:    Win_execute() does not set window pointers properly.
Solution:   Use switch_win_noblock().  Also execute autocommands in a popup
            window.
diff --git a/src/autocmd.c b/src/autocmd.c
index 21b9ab3..82b5868 100644
--- a/src/autocmd.c
+++ b/src/autocmd.c
@@ -1349,7 +1349,7 @@
      */
     FOR_ALL_BUFFERS(buf)
     {
-	if (buf->b_ml.ml_mfp != NULL && !bt_popup(buf))
+	if (buf->b_ml.ml_mfp != NULL)
 	{
 	    // find a window for this buffer and save some values
 	    aucmd_prepbuf(&aco, buf);
@@ -1612,8 +1612,6 @@
     int		force,	    // when TRUE, ignore autocmd_busy
     buf_T	*buf)	    // buffer for <abuf>
 {
-    if (bt_popup(buf))
-	return FALSE;
     return apply_autocmds_group(event, fname, fname_io, force,
 						      AUGROUP_ALL, buf, NULL);
 }