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)

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    484,
 /**/
     483,
 /**/