patch 8.0.0513: getting name of cleared highlight group is wrong

Problem:    Getting name of cleared highlight group is wrong. (Matt Wozniski)
Solution:   Only skip over cleared names for completion. (closes #1592)
            Also fix that a cleared group causes duplicate completions.
diff --git a/src/version.c b/src/version.c
index 3ebe8a6..28f3c59 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    513,
+/**/
     512,
 /**/
     511,