patch 8.1.0466: autocmd test fails

Problem:    Autocmd test fails.
Solution:   Do call inchar() when flushing typeahead.
diff --git a/src/misc1.c b/src/misc1.c
index 34b4134..820f8f9 100644
--- a/src/misc1.c
+++ b/src/misc1.c
@@ -3825,7 +3825,7 @@
 {
     if (emsg_silent == 0)
     {
-	flush_buffers(FALSE);
+	flush_buffers(FLUSH_MINIMAL);
 	vim_beep(BO_ERROR);
     }
 }