test: ignore the real XDG_CONFIG_HOME during tests Let's not have our tests fail if the user has an incompatible $XDG_CONFIG_HOME/xkb directory. libxkbcommon has fallbacks when XDG_CONFIG_HOME isn't set so we need to override this with a real directory instead of just unsetting it. Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>