Add script to update libuv from upstream

Utilities/Scripts/update-libuv.bash

@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+
+set -e
+set -x
+shopt -s dotglob
+
+readonly name="libuv"
+readonly ownership="libuv upstream <libuv@googlegroups.com>"
+readonly subtree="Utilities/cmlibuv"
+readonly repo="https://github.com/libuv/libuv.git"
+readonly tag="v1.x"
+readonly shortlog=false
+readonly paths="
+  LICENSE
+  include
+  src
+"
+
+extract_source () {
+    git_archive
+    pushd "${extractdir}/${name}-reduced"
+    echo "* -whitespace" > .gitattributes
+    popd
+}
+
+. "${BASH_SOURCE%/*}/update-third-party.bash"