Clean up more XFA code which causes warnings

xfa/fxbarcode/datamatrix/BC_DataMatrixDecodedBitStreamParser.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 228 matching lines @@
         case 3:
           if (upperShift) {
             result += (FX_CHAR)(cValue + 224);
             upperShift = FALSE;
           } else {
             result += (FX_CHAR)(cValue + 96);
           }
           shift = 0;
           break;
         default:
-          break;
+          // Should never be reached.
           e = BCExceptionFormatException;
           return;
       }
     }
   } while (bits->Available() > 0);
 }
 void CBC_DataMatrixDecodedBitStreamParser::DecodeTextSegment(
     CBC_CommonBitSource* bits,
     CFX_ByteString& result,
     int32_t& e) {
@@ skipping 70 matching lines @@
             } else {
               result += textChar;
             }
             shift = 0;
           } else {
             e = BCExceptionFormatException;
             return;
           }
           break;
         default:
-          break;
+          // Should never be reached.
           e = BCExceptionFormatException;
           return;
       }
     }
   } while (bits->Available() > 0);
 }
 void CBC_DataMatrixDecodedBitStreamParser::DecodeAnsiX12Segment(
     CBC_CommonBitSource* bits,
     CFX_ByteString& result,
     int32_t& e) {
@@ skipping 113 matching lines @@
   BC_FX_ByteString_Append(result, *bytes);
   delete bytes;
 }
 uint8_t CBC_DataMatrixDecodedBitStreamParser::Unrandomize255State(
     int32_t randomizedBase256Codeword,
     int32_t base256CodewordPosition) {
   int32_t pseudoRandomNumber = ((149 * base256CodewordPosition) % 255) + 1;
   int32_t tempVariable = randomizedBase256Codeword - pseudoRandomNumber;
   return (uint8_t)(tempVariable >= 0 ? tempVariable : tempVariable + 256);
 }