As part of the whole "for-host" thingy, we need to make build-essential
"Multi-Arch: same". Doing so is presently impossible as its
essential-package-list varies per architecture on a fixed filename.
Attempting to coinstall it would result in an unpack error.

To resolve this part, I propose encoding the architecture name into the
filename. I've checked for users of this file and found none, so the
move should be harmless. Please consider applying the attached patch.

Helmut