apfelxx, epic, partons*, sfml: new packages

[wdconinc]

This PR adds a stack of parton distribution function Monte Carlo packages (and multimedia package that they depend on for the only reason that it provides a Mutex class...).

• EpIC: https://github.com/pawelsznajder/epic
• PARTONS: https://github.com/3d-partons/partons
  • NumA++: https://github.com/3d-partons/numa
  • elementary-utils: https://github.com/3d-partons/elementary-utils
• Apfel++: https://github.com/vbertone/apfelxx
• SFML: https://github.com/SFML/SFML

Test builds (since epic and partons depends on the others, I hope this is sufficient; the rest is buried in a large environment):

-- linux-ubuntu26.04-skylake / %cxx=clang@23.0.0 ----------------
umgqbwq partons@5.0.0~ipo build_system=cmake build_type=Release generator=make
==> 1 installed package

and

-- linux-ubuntu26.04-skylake / %cxx=clang@23.0.0 ----------------
owxspn6 epic-generator@1.1.8~ipo build_system=cmake build_type=Release generator=make
==> 1 installed package

(I have a different local package that has the name epic, so I had to map builtin.epic onto epic-generator.)

[Copilot]

Pull request overview

This pull request adds several new Spack package recipes to support a small HEP Monte Carlo / PDF tooling stack (EpIC + PARTONS and their supporting libraries), including an sfml dependency.

Changes:

• Added new package recipes: apfelxx, epic, partons, partons-numa, partons-elementary-utils, and sfml.
• Declared dependency relationships between EpIC/PARTONS and the supporting libraries.
• Added basic CMake configuration via variants for sfml.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
repos/spack_repo/builtin/packages/sfml/package.py	New sfml CMake package with module variants and CMake configure flags.
repos/spack_repo/builtin/packages/partons/package.py	New partons CMake package with declared HEP/math dependencies.
repos/spack_repo/builtin/packages/partons_numa/package.py	New partons-numa CMake package and dependencies.
repos/spack_repo/builtin/packages/partons_elementary_utils/package.py	New partons-elementary-utils CMake package and dependencies.
repos/spack_repo/builtin/packages/epic/package.py	New epic CMake package with dependencies and custom install step.
repos/spack_repo/builtin/packages/apfelxx/package.py	New apfelxx CMake package with LHAPDF/yaml-cpp/pybind11 dependencies.

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[sethrj]

@wdconinc I can't test a couple of these due to the cln failure.