bug#26341: [PATCH 1/5] build: syscalls: Add reboot.

[Mathieu Othacehe <m.othacehe@gmail.com>]

Hey Ludo,

> The problem is that we cannot #:replace unconditionally (when not using
> the patched Guile, there’s nothing to replace¹).

Yes I was relying on #:replace ability to just export the symbol if
there's nothing to replace (as explained in your note¹).

>
> WDYT?

Anyway, your macro seems a nicer way than dealing with export/replace.
I gave it a try and everything still seems warning free.

My only concern is that it won't be obvious for people who want to use
reboot or mount or any other syscall that they have to use (guix build
syscalls) because the #:export list won't contain those syscalls.

Maybe a big explanation on top of the file would be enough ?

Thanks,

Mathieu