Update libwebp to 0.4.0

third_party/libwebp/enc/histogram.h

 // Copyright 2012 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)
 //
 // Models the histograms of literal and distance codes.
 
 #ifndef WEBP_ENC_HISTOGRAM_H_
 #define WEBP_ENC_HISTOGRAM_H_
 
 #include <assert.h>
 #include <stddef.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
 
 #include "./backward_references.h"
 #include "../webp/format_constants.h"
 #include "../webp/types.h"
 
-#if defined(__cplusplus) || defined(c_plusplus)
+#ifdef __cplusplus
 extern "C" {
 #endif
 
 // A simple container for histograms of data.
 typedef struct {
   // literal_ contains green literal, palette-code and
   // copy-length-prefix histogram
   int literal_[PIX_OR_COPY_CODES_MAX];
   int red_[256];
   int blue_[256];
@@ skipping 49 matching lines @@
       ((p->palette_code_bits_ > 0) ? (1 << p->palette_code_bits_) : 0);
 }
 
 // Builds the histogram image.
 int VP8LGetHistoImageSymbols(int xsize, int ysize,
                              const VP8LBackwardRefs* const refs,
                              int quality, int histogram_bits, int cache_bits,
                              VP8LHistogramSet* const image_in,
                              uint16_t* const histogram_symbols);
 
-#if defined(__cplusplus) || defined(c_plusplus)
+#ifdef __cplusplus
 }
 #endif
 
 #endif  // WEBP_ENC_HISTOGRAM_H_