Wrong bit-width check in CMake tooling.

[burnpanck]

We would like to use function_ref in an ARM embedded (32bit) use-case. We use a CMake superbuild approach to prepare dependencies, where CMAKE_TOOLCHAIN_FILE is properly passed to the sub-build, so the library should be built in 32bit mode. However, when trying to include the dependent library, CMake refuses to select the just-build library, claiming that it is 64bit and thus does not match our architecture. a) The library should really be built for a 32bit environment, somehow it thinks it is being built for a 64bit environment. b) As the library is header-only, the build environment should not matter, and therefore there should not be any bit-width check in the installed tl-function-ref-config-version.cmake.

[burnpanck]

It seems that write_basic_package_version_file offers an ARCH_INDEPENDENT option, which would probably be the right thing to do here. That would have to be passed through tl-cmake, so it's also a feature request over-there.