Install CMake config to architecture-specific location

[cottsay]

As an architecture-specific CMake project, the CMake config files should be installed to an architecture-specific location.

This issue was identified during the process of packaging apriltag for inclusion in Fedora Linux and EPEL[1]. You can see a similar patch was added to the debian build process for Ubuntu[2].

Related docs: https://cmake.org/cmake/help/latest/command/find_package.html#config-mode-search-procedure

[1] https://bugzilla.redhat.com/show_bug.cgi?id=2173758#c17
[2] https://salsa.debian.org/science-team/apriltag/-/blob/master/debian/patches/cmake-into-arch-specific-path.patch

[christian-rauch]

Thanks for pointing that out. The Debian patch changes that install path to lib/${CMAKE_LIBRARY_ARCHITECTURE}/cmake/${PROJECT_NAME}, you are proposing to change it to ${CMAKE_INSTALL_LIBDIR}/${PROJECT_NAME}/cmake. With this PR applied, doesn't this mean that Debian will still need to manually patch the CMakeLists.txt? Would it make more sense to just apply the patch that Debian is already applying? Then, they could directly use the upstream version.

[cottsay]

doesn't this mean that Debian will still need to manually patch the CMakeLists.txt?

On Debian, CMAKE_INSTALL_LIBDIR will resolve to lib/${CMAKE_LIBRARY_ARCHITECTURE}. I'm not really sure why the package maintainers patched it like that, but CMAKE_INSTALL_LIBDIR should do the same thing on Debian, but will also do the right thing on Fedora and RedHat where we want it to be lib64.

This should mean that neither Debian nor Fedora maintainers need to apply a patch for this.