feat: Add zeromq to enable RooFit multiprocessing (!67)
Closes #24 (closed)
* Build zeromq from source in root-base to provide a recent enough version
to support RooFit multiprocessing.
- c.f. https://github.com/root-project/root/pull/9078
* Enable RooFit multiprocessing in stats-base.
Edited by Matthew Feickert