libvpx: Pull from upstream

source/libvpx/vp8/encoder/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 "vpx_scale/yv12config.h"
-#include "math.h"
-#include "vp8/common/systemdependent.h" /* for vp8_clear_system_state() */
-
-#define MAX_PSNR 100
-
-double vp8_mse2psnr(double Samples, double Peak, double Mse)
-{
-    double psnr;
-
-    if ((double)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;
-}