Describe the bug

Building gcc twice does not necessarily result in the exact same binary. This makes auditing harder. For more information see https://reproducible-builds.org .

This is a particularly interesting case because gcc-10.2.0 is part of the build closure of nixos.iso_minimal, which we use as a milestone (https://r13y.com, https://arnout.engelen.eu/nixos-r13y/report/)