Remove unused code (#2013)

auth.go

@@ -5,7 +5,6 @@
 package gin
 
 import (
-	"crypto/subtle"
 	"encoding/base64"
 	"net/http"
 	"strconv"
@@ -86,11 +85,3 @@ func authorizationHeader(user, password string) string {
 	base := user + ":" + password
 	return "Basic " + base64.StdEncoding.EncodeToString([]byte(base))
 }
-
-func secureCompare(given, actual string) bool {
-	if subtle.ConstantTimeEq(int32(len(given)), int32(len(actual))) == 1 {
-		return subtle.ConstantTimeCompare([]byte(given), []byte(actual)) == 1
-	}
-	// Securely compare actual to itself to keep constant time, but always return false.
-	return subtle.ConstantTimeCompare([]byte(actual), []byte(actual)) == 1 && false
-}