There's a closed pull request on the void-packages repository

New package: CalculiX-2.20
https://github.com/void-linux/void-packages/pull/39984

Description:
### NEW PACKAGE - CalculiX

This new package conforms to the [package requirements](https://github.com/void-linux/void-packages/blob/master/CONTRIBUTING.md#package-requirements): **YES**

CalculiX is a 3D finite element program. It is an optional but important dependency of FreeCAD (for mechanical and thermal calculations). This PR is related to issue https://github.com/void-linux/void-packages/issues/5603.

CalculiX is split in two parts: the solver (CalculiX-ccx) and the graphical interface and pre/post-processing (CalculiX-cgx).

This PR includes 4 packages, each in a separate commit:
- spooles (build dependency for CalculiX-ccx)
- CalculiX-ccx
- CalculiX-cgx (including tetgen binary)
- CalculiX meta-package (which brings CalculiX-ccx and CalculiX-cgx)


### Tests
#### Local build testing
- Native x86_64 (glibc and musl): **OK**
- Native i686 (glibc) (from an x86_64 machine) : **OK**
- Native armv7l (glibc): **OK**

#### Cross build testing (from x86_64 machine)
- Cross-compiling to armv7l: **OK** (requires using `./xbps-src binary-boostrap i686` on an x86_64 system, otherwise it fails)
- Cross-compiling to aarch64: **OK**

#### Runtime testing
- On x86_64 (glibc): **OK** (for CalculiX-ccx: some calculation tests differ from the official reference results files)
- On armv7l: **OK** (for CalculiX-ccx: some calculation differences too)
- On i686: **NOT TESTED**