prometheus-hacluster-exporter fails to cross build from source, because
it encounters an Exec format error running the Go compiler. In
principle, we would have to turn golang-any M-A:foreign, but that would
been broken when using gccgo-go. Now that gccgo-go is no more, we can
directly depend on golang-go and there we can add a :native annotation.
dh-golang has been fixed to pass suitable cross compilation flags a
while ago, so just changing the dependency makes it cross buildable.
Please consider applying the attached patch.

Helmut