Get rid of NULLs in xfa/fxbarcode/

xfa/fxbarcode/datamatrix/BC_DataMatrixDataBlock.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 2008 ZXing authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ skipping 72 matching lines @@
     for (int32_t j = 0; j < numResultBlocks; j++) {
       int32_t iOffset = specialVersion && j > 7 ? i - 1 : i;
       if (rawCodewordsOffset < rawCodewords->GetSize()) {
         (*result)[j]->GetCodewords()->operator[](iOffset) =
             (*rawCodewords)[rawCodewordsOffset++];
       }
     }
   }
   if (rawCodewordsOffset != rawCodewords->GetSize()) {
     e = BCExceptionIllegalArgument;
-    return NULL;
+    return nullptr;
   }
   return result.release();
 }
 
 int32_t CBC_DataMatrixDataBlock::GetNumDataCodewords() {
   return m_numDataCodewords;
 }
 CFX_ByteArray* CBC_DataMatrixDataBlock::GetCodewords() {
   return &m_codewords;
 }