UXP/modules/woff2

This is the woff2 library from
https://github.com/google/woff2.

Upstream code can be viewed at
  https://github.com/google/woff2/tree/master

and cloned by
  git clone https://github.com/google/woff2

The in-tree copy is updated by running
  sh update.sh
from within the modules/woff2 directory.

Currently no patching is needed. (Let's keep it that way if we can!)

Current version: [commit 4721483ad780ee2b63cb787bfee4aa64b61a0446].