bug#20272: Support reproducible builds

[Andy Wingo]

On Thu 22 Dec 2016 00:53, address@hidden (Ludovic Courtès) writes:

> +(define (module-generate-unique-id! m)
> +  (let ((i (module-next-unique-id m)))
> +    (set-module-next-unique-id! m (+ i 1))
> +    i))

This introduces a race condition when expanding from multiple threads at
once.  Any plan here?

Andy