[JIRA] (BIT-1407) -f silently fails if base/frameworks/packet-filter isn't loaded

Yeah, I can see that. I think the main problem is the interaction
between the command-line option and script, something that's rare
(i.e., that the command-line option is tight that closely to a script
being loaded). I would actually suggest we remove the command-line
option altogether and instead work with a global: "bro -i eth0
PacketFilter::filter=XXXX" (I believe we have a global with that
effect already, otherwise we could add it).


We could alternately take the additional step of moving command line argument processing into Bro scripts. I don’t know how exactly we’d solve this particular problem, but it should be reasonably solvable that way.