Setting TMPDIR for Guix

[pelzflorian (Florian Pelz)]

Hello,

I suspect some package builds fail for me because I have only 2GB of RAM
and /tmp may be full. Either way, I want to use a different TMPDIR
environment variable for the Guix daemon.

I’d like to
1) start guix-daemon with an environment in which TMPDIR is set to
/tmpdir and
2) change my Guix system configuration so that it automatically creates
a /tmpdir directory.

On systemd I just change the TMPDIR for Guix using `systemctl edit
guix-daemon` but how do I set this environment variable on GuixSD?

I cannot find this information in `info guix` but maybe I should have
searched more carefully.

Regards,
Florian