libvpx: Pull from upstream

source/libvpx/tools_common.c

 /*
  *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE 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.
  */
 
@@ skipping 228 matching lines @@
   int plane;
 
   for (plane = 0; plane < 3; ++plane) {
     unsigned char *buf = img->planes[plane];
     const int stride = img->stride[plane];
     const int w = vpx_img_plane_width(img, plane);
     const int h = vpx_img_plane_height(img, plane);
     int y;
 
     for (y = 0; y < h; ++y) {
-      if (fread(buf, 1, w, file) != w)
+      if (fread(buf, 1, w, file) != (size_t)w)
         return 0;
       buf += stride;
     }
   }
 
   return 1;
 }
 
 // TODO(dkovalev) change sse_to_psnr signature: double -> int64_t
 double sse_to_psnr(double samples, double peak, double sse) {
   static const double kMaxPSNR = 100.0;
 
   if (sse > 0.0) {
     const double psnr = 10.0 * log10(samples * peak * peak / sse);
     return psnr > kMaxPSNR ? kMaxPSNR : psnr;
   } else {
     return kMaxPSNR;
   }
 }