Updating Opus to a pre-release of 1.1

This CL updates Opus to a pre-release of the coming Opus 1.1 version. The code is extracted from http://git.xiph.org/?p=opus.git, commit aee4d8057632ea0cfc1d55d88acf8466b47b7b4b from October 1st 2013.
This version includes both algorithmic and platform optimizations, as well an important fix for a denorm problem when the input goes silent after active audio. The problem causes high CPU usage.

Review URL: https://codereview.chromium.org/28553003

git-svn-id: svn://svn.chromium.org/chrome/trunk/deps/third_party/opus@230378 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/celt/entdec.c b/celt/entdec.c
index 75e3e45..3c26468 100644
--- a/celt/entdec.c
+++ b/celt/entdec.c
@@ -85,7 +85,7 @@
    number=3,
    pages="256--294",
    month=Jul,
-   URL="http://www.stanford.edu/class/ee398/handouts/papers/Moffat98ArithmCoding.pdf"
+   URL="http://www.stanford.edu/class/ee398a/handouts/papers/Moffat98ArithmCoding.pdf"
   }*/
 
 static int ec_read_byte(ec_dec *_this){