libvpx: Pull from upstream

source/libvpx/vp9/encoder/vp9_psnr.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.
  */
 
+#include <math.h>
 
 #include "vpx_scale/yv12config.h"
-#include "math.h"
 
 #define MAX_PSNR 100
 
 double vp9_mse2psnr(double samples, double peak, double mse) {
   double psnr;
 
   if (mse > 0.0)
     psnr = 10.0 * log10(peak * peak * samples / mse);
   else
     psnr = MAX_PSNR;  // Limit to prevent / 0
 
   if (psnr > MAX_PSNR)
     psnr = MAX_PSNR;
 
   return psnr;
 }