Solution: install it if available. Download it from its repo as part
of the OBS source run.
Debian and Ubuntu always ship zmq.hpp in libzmq-dev, so do the same.
In the RPM world it is in its own separate package, so don't do the
same for RPM.
Solution: a new option has been added to the tar_scm service, so use
it to set the version to last_tag+git<last commit date> which is more
useful.
Unfortunately it's not possible to set it to the current version as
set in the header files, as it's not possible to parse files, only
commit ids, dates and git tags. But it's a step forward.
