Subject: Guix fails to build with libgc 8.0.4

From: Jonathan Brielmaier <[email-masked]>
Date: Mon, 3 Feb 2020 12:49:53 +0100

Just for the record: Ludo added libgc-8 in
69961ac3b9db2dbb99abb5c45ff6be3a9c01b5de on master. It's not yet used,
so we need to replace libgc-7.6 with it and see how it goes...