Add script to update LibArchive from upstream

Utilities/Scripts/update-libarchive.bash

+#!/usr/bin/env bash
+
+set -e
+set -x
+shopt -s dotglob
+
+readonly name="LibArchive"
+readonly ownership="LibArchive Upstream <libarchive-discuss@googlegroups.com>"
+readonly subtree="Utilities/cmlibarchive"
+readonly repo="https://github.com/libarchive/libarchive.git"
+readonly tag="master"
+readonly shortlog=false
+readonly paths="
+  CMakeLists.txt
+  COPYING
+  CTestConfig.cmake
+  build/cmake
+  build/pkgconfig
+  build/utils
+  build/version
+  libarchive/*.*
+"
+
+extract_source () {
+    git_archive
+    pushd "${extractdir}/${name}-reduced"
+    fromdos build/cmake/Find*.cmake
+    popd
+}
+
+. "${BASH_SOURCE%/*}/update-third-party.bash"