travis: test cross platform compile
travis: test cross platform compile

trying to allow cross-platform to fail for now, using env variables as
seen in
https://docs.travis-ci.com/user/customizing-the-build/#Rows-that-are-Allowed-to-Fail

Signed-off-by: Vincent Batts <d01a4772f0cffd3f005a7d7f01c59cd104c7a5fe@hashbangbash.com>

jwhonce/ocid,nalind/cri-o,rhatdan/cri-o,jwhonce/ocid,jwhonce/ocid,mikebrow/cri-o,rhatdan/cri-o,nalind/cri-o,kubernetes-incubator/ocid,vbatts/cri-o,nalind/cri-o,vbatts/cri-o,rhatdan/cri-o,vbatts/cri-o,mikebrow/cri-o,mikebrow/cri-o,kubernetes-incubator/cri-o,kubernetes-incubator/ocid,kubernetes-incubator/cri-o,vbatts/cri-o,rhatdan/cri-o,kubernetes-incubator/ocid,kubernetes-incubator/cri-o,mikebrow/cri-o,kubernetes-incubator/cri-o