Fix the logic for skipping parameters (with -s) that have "jailsys"
parents (such as host.hostname); these were being skipped all the time.
That it went this long without anyone noticing is a sign that this feature
isn't actually used by anyone, but it's there so it might as well work.

Allow for parameters added with the JP_OPT flag to not exist.
That's why the flag exists in the first place.