Make code more portable + remove mcookie usage

Signed-off-by: AnErrupTion <anerruption@disroot.org>

src/config/Lang.zig

@@ -12,7 +12,6 @@ err_dgn_oob: []const u8 = "log message",
 err_domain: []const u8 = "invalid domain",
 err_envlist: []const u8 = "failed to get envlist",
 err_hostname: []const u8 = "failed to get hostname",
-err_mcookie: []const u8 = "mcookie command failed",
 err_mlock: []const u8 = "failed to lock password memory",
 err_null: []const u8 = "null pointer",
 err_pam: []const u8 = "pam transaction failed",