`make-based`: Add `do_aarch64.sh` script for Helloworld to work on `aarch64`

Add a `do_aarch64.sh` script for `make-based/app-helloworld/` to make it work for ARM64 / `aarch64`.

See the [`do-sqlite-aarch64` script for Musl](https://github.com/unikraft-upb/scripts/blob/main/musl/do-sqlite-aarch64).

Make sure you validate the script with [`shellcheck`](https://www.shellcheck.net/).

**Hackathon points**: 20