.gitignore: Ignore /.gopathok
.gitignore: Ignore /.gopathok

We've been occasionally creating this file since 9c44933b (build:
create a local GOPATH if none specified, 2017-03-27, #410).  But it's
recording information about the local environment, not part of our
common source.  Adding it to .gitignore helps avoid having it
accidentally committed.

Signed-off-by: W. Trevor King <f75897670c17327c42ab201733fb8a81ff9f4c34@tremily.us>

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