patch 8.0.0484: :lhelpgrep does not fail after a successful one

Problem:    Using :lhelpgrep with an argument that should fail does not
            produce an error if the previous :helpgrep worked.
Solution:   Use another way to detect that autocommands made the quickfix info
            invalid. (Yegappan Lakshmanan)
diff --git a/src/version.c b/src/version.c
index bb4cadc..34c1aab 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    484,
+/**/
     483,
 /**/
     482,