Could you try out the patch in this email?

Now, the problem is that GCC is configured with the native ld.so as the 
target system's dynamic linker.

I'm not sure what code is responsible for that, but on the wip-hurd 
branch, this exact same problem happens for other platforms as well.

In particular, it happened when I tried:
$ ./pre-inst-env guix build coreutils --target=i686-pc-linux-gnu -K
on an x86_64 box.

-- 
Marek.