Adapt update script to avoid downloading again and reuse release files

set -e

if [ $# -ne 1 ]; then

  echo "usage: $0 VERSION"

if [ $# -ne 2 ]; then

  echo "usage: $0 VERSION RELEASE_DIRECTORY"

  exit 1

fi

version="$1"

release_directory="$2"

file="share/ruby-build/truffleruby-${version}"

add_platform() {

  platform="$1"

  basename="truffleruby-${version}-${platform}.tar.gz"

  url="https://github.com/oracle/truffleruby/releases/download/vm-${version}/${basename}"

  sha256=$(curl -L "$url" | sha256sum | cut -d ' ' -f 1)

  sha256=$(sha256sum "$release_directory/$basename" | cut -d ' ' -f 1)

  cat >> "$file" <<EOS

  install_package "truffleruby-${version}" "${url}#${sha256}" truffleruby