hswg: deduplicate backlinks

hswg/main.go

@@ -236,10 +236,13 @@ func main() {
 
 		sort.Strings(e.backlinks)
 
-		backlinks := []string{}
+		backlinks, last := []string{}, ""
 		for _, name := range e.backlinks {
+			if name != last {
 				backlinks = append(backlinks, makeLink(&entries, name))
 			}
+			last = name
+		}
 
 		if len(backlinks) > 0 {
 			_, _ = f.WriteString(fmt.Sprintf("<p id=links>Links here: %s</p>\n",