google-compute-engine-oslogin fails to cross build from source, because
it uses the build architecture compiler. Looking closer, this happens
during dh_auto_install where debhelper does not pass cross tools.
Apparently, it performs some of the build steps during dh_auto_install.
I tracked this down to not setting the VERSION variable during
dh_auto_build. Once setting it, make install doesn't build anything
anymore and the cross build succeeds. I'm attaching a patch for your
convenience.

Helmut