add option to use compiled binaries of superlu

[looooo]

conda-forge has a build for superlu: https://anaconda.org/conda-forge/superlu

It would be nice if the cmake configuration has an option to use a installed version of superlu. Something like:

find_package(superlu)

[Bruno02468]

The C-Fortran integration with SuperLU was done in a way that still requires the SuperLU source to be present... once I get rid of that, we can just link against SuperLU directly.

That's a good suggestion.

[looooo]

another thing that came up while trying to build mystran: It would be nice if binaries are installed into $PREFIX/bin: install(TARGETS mystran DESTINATION${CMAKE_INSTALL_PREFIX}/bin)

Currently only the superlu libraries are installed via cmake:

Install the project...
-- Install configuration: "Release"
-- Installing: /Users/lo/projects/freecad/MYSTRAN/.pixi/envs/default/lib/pkgconfig/superlu.pc
-- Installing: /Users/lo/projects/freecad/MYSTRAN/.pixi/envs/default/lib/libsuperlu.a
-- Up-to-date: /Users/lo/projects/freecad/MYSTRAN/.pixi/envs/default/include/supermatrix.h
-- Up-to-date: /Users/lo/projects/freecad/MYSTRAN/.pixi/envs/default/include/slu_Cnames.h
-- Up-to-date: /Users/lo/projects/freecad/MYSTRAN/.pixi/envs/default/include/slu_dcomplex.h
-- Up-to-date: /Users/lo/projects/freecad/MYSTRAN/.pixi/envs/default/include/slu_scomplex.h
-- Up-to-date: /Users/lo/projects/freecad/MYSTRAN/.pixi/envs/default/include/slu_util.h
-- Up-to-date: /Users/lo/projects/freecad/MYSTRAN/.pixi/envs/default/include/superlu_enum_consts.h
-- Installing: /Users/lo/projects/freecad/MYSTRAN/.pixi/envs/default/include/superlu_config.h
-- Up-to-date: /Users/lo/projects/freecad/MYSTRAN/.pixi/envs/default/include/slu_sdefs.h
-- Up-to-date: /Users/lo/projects/freecad/MYSTRAN/.pixi/envs/default/include/slu_ddefs.h
-- Up-to-date: /Users/lo/projects/freecad/MYSTRAN/.pixi/envs/default/include/slu_cdefs.h
-- Up-to-date: /Users/lo/projects/freecad/MYSTRAN/.pixi/envs/default/include/slu_zdefs.h
-- Installing: /Users/lo/projects/freecad/MYSTRAN/.pixi/envs/default/lib/cmake/superlu/superluTargets.cmake
-- Installing: /Users/lo/projects/freecad/MYSTRAN/.pixi/envs/default/lib/cmake/superlu/superluTargets-release.cmake
-- Installing: /Users/lo/projects/freecad/MYSTRAN/.pixi/envs/default/lib/cmake/superlu/superluConfig.cmake
-- Installing: /Users/lo/projects/freecad/MYSTRAN/.pixi/envs/default/lib/cmake/superlu/superluConfigVersion.cmake