libvpx: Pull from upstream

source/libvpx/vp9/encoder/vp9_avg.c

+/*
+ *  Copyright (c) 2014 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 "vp9/common/vp9_common.h"
+#include "vpx_ports/mem.h"
+
+unsigned int vp9_avg_8x8_c(const uint8_t *s, int p) {
+  int i, j;
+  int sum = 0;
+  for (i = 0; i < 8; ++i, s+=p)
+    for (j = 0; j < 8; sum += s[j], ++j) {}
+
+  return (sum + 32) >> 6;
+}
+
+#if CONFIG_VP9_HIGHBITDEPTH
+unsigned int vp9_highbd_avg_8x8_c(const uint8_t *s8, int p) {
+  int i, j;
+  int sum = 0;
+  const uint16_t* s = CONVERT_TO_SHORTPTR(s8);
+  for (i = 0; i < 8; ++i, s+=p)
+    for (j = 0; j < 8; sum += s[j], ++j) {}
+
+  return (sum + 32) >> 6;
+}
+#endif  // CONFIG_VP9_HIGHBITDEPTH
+