No `hurd-i386` and `hurd-amd64` variants of `crossbuild-essential-*`.

[Yuqian Yang <crupest@crupest.life>]

Hello!

I found that Debian lacks `hurd-i386` and `hurd-amd64` variants of 
`crossbuild-essential-*`[1]. I wonder whether this is intentional, or we 
can just add these two.

Thanks!

[1] https://sources.debian.org/src/build-essential/12.12/debian/control/

--
Yuqian Yang <crupest@crupest.life>