Support for HiPE compiler

[astawiarski]

Added support for enabling HiPE compiler through RABBITMQ_HIPE_COMPILE environment variable

[astawiarski]

I've created a corresponding pull request in documentation: docker-library/docs#476

[tianon]

Sorry for the delay! I'm +1 on the HiPE change in general (making it available conditionally), but I think this block could use some improvement, and here's what I'd propose instead:

for conf in "${configs[@]}"; do
    var="RABBITMQ_${conf^^}"
    val="${!var}"
    rawVal=
    case "$conf" in
        # SSL-related options are configured above, so should be ignored here
        ssl_*) continue ;;

        # convert shell booleans into Erlang booleans
        hipe_compile)
            [ "$val" ] && rawVal='true' || rawVal='false'
            ;;

        # otherwise, assume string-based (and skip or add appropriate decorations)
        *)
            [ "$val" ] || continue
            rawVal='<<"'"$val"'">>'
            ;;
    esac
    cat >> /etc/rabbitmq/rabbitmq.config <<-EOC
        {$conf, $rawVal},
    EOC
done

(I'm happy to take over the PR from here as well, if you'd rather, taking your commits and making a new PR that implements this case. 👍)

[astawiarski]

Thanks for the comment and suggestion, it's a great lesson! Please feel free to take over