Tweak OTA mask

sync with shadowsocks-libev

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

shadowsocks-csharp/Encryption/IVEncryptor.cs

@@ -106,7 +106,7 @@ namespace Shadowsocks.Encryption
         #region OneTimeAuth
 
         public const int ONETIMEAUTH_FLAG = 0x10;
-        public const int ADDRTYPE_MASK = 0xF;
+        public const int ADDRTYPE_MASK = 0xEF;
 
         public const int ONETIMEAUTH_BYTES = 10;