release-debian: generate empty i386 Packages file
release-debian: generate empty i386 Packages file

`apt-get update` tries to find package listings for all architectures on
multi-arch systems. (It probably shouldn't do that when the repository
only advertises one architecture.)

To work around this in the most common case of having i386 configured on
an amd64 system, generate an empty Packages file for i386.

Closes #53
Reviewed-by: Stef Walter <8a7fbf0f15d3ad982af54ef28f5c117d2494b76c@redhat.com>

cockpit-project/cockpituous,stefwalter/cockpituous,stefwalter/cockpituous,cockpit-project/cockpituous