Revert r97185 "Update libvpx snapshot to v0.9.7-p1 (Cayuga)."

libvpx/source/libvpx/vp8/decoder/treereader.h

Index: libvpx/source/libvpx/vp8/decoder/treereader.h
diff --git a/libvpx/source/libvpx/vp8/decoder/treereader.h b/libvpx/source/libvpx/vp8/decoder/treereader.h
index 238ff853612ed588ba9bb19800ced203bef567f1..b50a4d2ff39f5af53290862e7f95ae40cd8022af 100644
--- a/libvpx/source/libvpx/vp8/decoder/treereader.h
+++ b/libvpx/source/libvpx/vp8/decoder/treereader.h
@@ -38,4 +38,27 @@ static int vp8_treed_read(
     return -i;
 }
 
+
+/* Variant reads a binary number given distributions on each bit.
+   Note that tree is arbitrary; probability of decoding a zero
+   may or may not depend on previously decoded bits. */
+
+static int vp8_treed_read_num(
+    vp8_reader *const r,        /* !!! must return a 0 or 1 !!! */
+    vp8_tree t,
+    const vp8_prob *const p
+)
+{
+    vp8_tree_index i = 0;
+    int v = 0, b;
+
+    do
+    {
+        b = vp8_read(r, p[i>>1]);
+        v = (v << 1) + b;
+    }
+    while ((i = t[i+b]) > 0);
+
+    return v;
+}
 #endif /* tree_reader_h */