lammps: added build dependency to py-setuptools

[prs513rosewood]

LAMMPS' setup.py uses setuptools as of lammps/lammps@2ed8e5cf022. For some reason, installing lammps+python did not report a failed build if setuptools was missing, causing an incomplete install.

Question: when built with python bindings, LAMMPS does not extends("python"), should it?

[spackbot-app]

Hi @prs513rosewood! I noticed that the following package(s) don't yet have maintainers:

• lammps

Are you interested in adopting any of these package(s)? If so, simply add the following to the package class:

    maintainers = ['prs513rosewood']

If not, could you contact the developers of this package and see if they are interested? You can quickly see who has worked on a package with spack blame:

$ spack blame lammps

Thank you for your help! Please don't add maintainers without their consent.

You don't have to be a Spack expert or package developer in order to be a "maintainer," it just gives us a list of users willing to review PRs or debug issues relating to this package. A package can have multiple maintainers; just add a list of GitHub handles of anyone who wants to volunteer.

[tldahlgren]

LGTM

[tldahlgren]

Question: when built with python bindings, LAMMPS does not extends("python"), should it?

Depends. There's a rule of thumb given at https://spack.readthedocs.io/en/latest/build_systems/pythonpackage.html?highlight=extends#extends-vs-depends-on.

I'm going to assume if you want to make the change it will be in a different PR.