Subject: [bug#38612] Pass system and target arguments to gexp->file.

From: Mathieu Othacehe <[email-masked]>
Date: Thu, 26 Dec 2019 19:19:06 +0100

Hey Ludo,

> LGTM!
>
> Does it fix something for you?

Thanks for your review :) Yes, without this patch, all
operating-system-packages are built for host system instead of target,
when cross-compiling a Guix System.

Mathieu