We build ZMQ locally to the erlang zmq library instead of using libzmq as built by omnibus.

[markan]

This is here for tracking before we do our next release.

We've observed that in the erlang zmq library is building a local copy of zmq instead of using the omnibus zmq. That is problematic because that is fragile and dependent on things like the python version available.

This was observed in the buildkite tests, and worked around, but should also be checked fixed for omnibus.

[markan]

To be a little more specific, building the local zmq requires python2, which is nearing end of life. The omnibus build handles this properly, and we'd like to use that instead of the unstable local build.