Remove set but unsed variables.

xfa/src/fxbarcode/datamatrix/BC_TextEncoder.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 // Original code is licensed as follows:
 /*
  * Copyright 2006-2007 Jeremias Maerki.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ skipping 32 matching lines @@
     return 1;
   }
   if (c >= '0' && c <= '9') {
     sb += (FX_WCHAR)(c - 48 + 4);
     return 1;
   }
   if (c >= 'a' && c <= 'z') {
     sb += (FX_WCHAR)(c - 97 + 14);
     return 1;
   }
-  if (c >= '\0' && c <= 0x1f) {
+  if (c <= 0x1f) {
     sb += (FX_WCHAR)'\0';
     sb += c;
     return 2;
   }
   if (c >= '!' && c <= '/') {
     sb += (FX_WCHAR)'\1';
     sb += (FX_WCHAR)(c - 33);
     return 2;
   }
   if (c >= ':' && c <= '@') {
@@ skipping 25 matching lines @@
     sb += (FX_WCHAR)'\1';
     sb += (FX_WCHAR)0x001e;
     int32_t len = 2;
     len += encodeChar((FX_WCHAR)(c - 128), sb, e);
     BC_EXCEPTION_CHECK_ReturnValue(e, -1);
     return len;
   }
   CBC_HighLevelEncoder::illegalCharacter(c, e);
   return -1;
 }