I don't have libgcc1-amd64-cross package, because I can't build my cross-gcc, of course.
I thick you need to use dpkg-cross for that.
Try
Get libgcc1 (crossed arch version) from a mirror
$ dpkg-cross -a ${ARCH} -b ${deb_file}
$ dpkg --force-depends -i <package>
I believe you need to use (latest) dpkg-cross 1.32.
Are you quite sure that the reason of my problem is missing package(s)? Maybe building process should link my cross-gcc against libs from /usr/lib/, not from /usr/x86_64-linux/lib/? Unfortunately, I'm not a gcc expert.
I do not consider myself an expert either, but as I said it is known that cross compiler you are trying to build does not built. Regards, Hector Oron