libvpx: Pull from upstream

source/libvpx/vpxstats.h

 /*
  *  Copyright (c) 2013 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 18 matching lines @@
   char *buf_ptr;
   size_t buf_alloc_sz;
 } stats_io_t;
 
 int stats_open_file(stats_io_t *stats, const char *fpf, int pass);
 int stats_open_mem(stats_io_t *stats, int pass);
 void stats_close(stats_io_t *stats, int last_pass);
 void stats_write(stats_io_t *stats, const void *pkt, size_t len);
 vpx_fixed_buf_t stats_get(stats_io_t *stats);
 
-double vp8_mse2psnr(double samples, double peak, double mse);
-
 #ifdef __cplusplus
 }  // extern "C"
 #endif
 
 #endif  // VPXSTATS_H_