Port folder renaming changes from AOM

Manually cherry-picked commits:
ceef058 libvpx->libaom part2
3d26d91 libvpx -> libaom
cfea7dd vp10/ -> av1/
3a8eff7 Fix a build issue for a test
bf4202e Rename vpx to aom

Change-Id: I1b0eb5a40796e3aaf41c58984b4229a439a597dc

av1/encoder/variance_tree.c

@@ -0,0 +1,60 @@
+/*
+ *  Copyright (c) 2016 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 "av1/encoder/variance_tree.h"
+#include "av1/encoder/encoder.h"
+
+void vp10_setup_var_tree(struct VP10Common *cm, ThreadData *td) {
+  int i, j;
+#if CONFIG_EXT_PARTITION
+  const int leaf_nodes = 1024;
+  const int tree_nodes = 1024 + 256 + 64 + 16 + 4 + 1;
+#else
+  const int leaf_nodes = 256;
+  const int tree_nodes = 256 + 64 + 16 + 4 + 1;
+#endif  // CONFIG_EXT_PARTITION
+  int index = 0;
+  VAR_TREE *this_var;
+  int nodes;
+
+  vpx_free(td->var_tree);
+  CHECK_MEM_ERROR(cm, td->var_tree,
+                  vpx_calloc(tree_nodes, sizeof(*td->var_tree)));
+
+  this_var = &td->var_tree[0];
+
+  // Sets up all the leaf nodes in the tree.
+  for (index = 0; index < leaf_nodes; ++index) {
+    VAR_TREE *const leaf = &td->var_tree[index];
+    leaf->split[0] = NULL;
+  }
+
+  // Each node has 4 leaf nodes, fill in the child pointers
+  // from leafs to the root.
+  for (nodes = leaf_nodes >> 2; nodes > 0; nodes >>= 2) {
+    for (i = 0; i < nodes; ++i, ++index) {
+      VAR_TREE *const node = &td->var_tree[index];
+      for (j = 0; j < 4; j++) node->split[j] = this_var++;
+    }
+  }
+
+  // Set up the root node for the largest superblock size
+  i = MAX_MIB_SIZE_LOG2 - MIN_MIB_SIZE_LOG2;
+  td->var_root[i] = &td->var_tree[tree_nodes - 1];
+  // Set up the root nodes for the rest of the possible superblock sizes
+  while (--i >= 0) {
+    td->var_root[i] = td->var_root[i + 1]->split[0];
+  }
+}
+
+void vp10_free_var_tree(ThreadData *td) {
+  vpx_free(td->var_tree);
+  td->var_tree = NULL;
+}