Also split the unit tests into those that are actually Linux-specific and those that are not and can (and should) run on all platforms. This will give us much better coverage since a lot of these test platform-specific code in Meson that wraps features that we expose in a platform-agnostic way. Tests are for: https://github.com/mesonbuild/meson/issues/1341 https://github.com/mesonbuild/meson/issues/1345 https://github.com/mesonbuild/meson/issues/1349