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

aom_dsp/bitreader_buffer.c

@@ -0,0 +1,46 @@
+/*
+ *  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.
+ */
+#include "./vpx_config.h"
+#include "./bitreader_buffer.h"
+
+size_t vpx_rb_bytes_read(struct vpx_read_bit_buffer *rb) {
+  return (rb->bit_offset + 7) >> 3;
+}
+
+int vpx_rb_read_bit(struct vpx_read_bit_buffer *rb) {
+  const size_t off = rb->bit_offset;
+  const size_t p = off >> 3;
+  const int q = 7 - (int)(off & 0x7);
+  if (rb->bit_buffer + p < rb->bit_buffer_end) {
+    const int bit = (rb->bit_buffer[p] >> q) & 1;
+    rb->bit_offset = off + 1;
+    return bit;
+  } else {
+    rb->error_handler(rb->error_handler_data);
+    return 0;
+  }
+}
+
+int vpx_rb_read_literal(struct vpx_read_bit_buffer *rb, int bits) {
+  int value = 0, bit;
+  for (bit = bits - 1; bit >= 0; bit--) value |= vpx_rb_read_bit(rb) << bit;
+  return value;
+}
+
+int vpx_rb_read_signed_literal(struct vpx_read_bit_buffer *rb, int bits) {
+  const int value = vpx_rb_read_literal(rb, bits);
+  return vpx_rb_read_bit(rb) ? -value : value;
+}
+
+int vpx_rb_read_inv_signed_literal(struct vpx_read_bit_buffer *rb, int bits) {
+  const int nbits = sizeof(unsigned) * 8 - bits - 1;
+  const unsigned value = (unsigned)vpx_rb_read_literal(rb, bits + 1) << nbits;
+  return ((int)value) >> nbits;
+}