remove redondant variable declaration

cmd/wireformat/wireformat.go

@@ -22,13 +22,11 @@ func main() {
 	// remove timestamp prefix from log out
 	log.SetFlags(0)
 
-	var body []byte
-	var err error
 	if *file != "" {
 		if *file == "-" {
 			*file = os.Stdin.Name()
 		}
-		body, err = ioutil.ReadFile(*file)
+		body, err := ioutil.ReadFile(*file)
 		check.Check(err)
 
 		msg := &dns.Msg{}