Update libwebp to 0.4.0

third_party/libwebp/utils/huffman_encode.h

 // Copyright 2011 Google Inc. All Rights Reserved.
 //
 // Use of this source code is governed by a BSD-style license
 // that can be found in the COPYING file in the root of the source
 // tree. An additional intellectual property rights grant can be found
 // in the file PATENTS. All contributing project authors may
 // be found in the AUTHORS file in the root of the source tree.
 // -----------------------------------------------------------------------------
 //
 // Author: Jyrki Alakuijala (jyrki@google.com)
 //
 // Entropy encoding (Huffman) for webp lossless
 
 #ifndef WEBP_UTILS_HUFFMAN_ENCODE_H_
 #define WEBP_UTILS_HUFFMAN_ENCODE_H_
 
 #include "../webp/types.h"
 
-#if defined(__cplusplus) || defined(c_plusplus)
+#ifdef __cplusplus
 extern "C" {
 #endif
 
 // Struct for holding the tree header in coded form.
 typedef struct {
   uint8_t code;         // value (0..15) or escape code (16,17,18)
   uint8_t extra_bits;   // extra bits for escape codes
 } HuffmanTreeToken;
 
 // Struct to represent the tree codes (depth and bits array).
 typedef struct {
   int       num_symbols;   // Number of symbols.
   uint8_t*  code_lengths;  // Code lengths of the symbols.
   uint16_t* codes;         // Symbol Codes.
 } HuffmanTreeCode;
 
 // Turn the Huffman tree into a token sequence.
 // Returns the number of tokens used.
 int VP8LCreateCompressedHuffmanTree(const HuffmanTreeCode* const tree,
                                     HuffmanTreeToken* tokens, int max_tokens);
 
 // Create an optimized tree, and tokenize it.
 int VP8LCreateHuffmanTree(int* const histogram, int tree_depth_limit,
                           HuffmanTreeCode* const tree);
 
-#if defined(__cplusplus) || defined(c_plusplus)
+#ifdef __cplusplus
 }
 #endif
 
 #endif  // WEBP_UTILS_HUFFMAN_ENCODE_H_