Set -e in cross build
Set -e in cross build

This was ignoring errors in CI.

Signed-off-by: Justin Cormack <af64ee19f04db9509cb02b0e470e11e5402ef9b3@docker.com>

endophage/notary,johnsandiford/notary,endophage/notary,HuKeping/notary,johnsandiford/notary,johnsandiford/notary,jfrazelle/notary,docker/notary,HuKeping/notary,endophage/notary,docker/notary,HuKeping/notary,docker/notary,jfrazelle/notary,jfrazelle/notary