Making start/stop idempotent

Our management tools like processes to be idempotent; i.e., you should
be able to start or stop a process any number of times without it
throwing an error.

Currently, Squid will return 1 if a squid process is already running
(upon start) and when there isn't one (upon -k shutdown).

I'm writing a patch to change this behaviour, and the most reasonable
way to do it seems to be with a command-line option; I've somewhat
arbitrarily chosen -p.

Does this seem reasonable? If so, I'll submit a patch shortly.

Cheers,

--
Mark Nottingham       mnot_at_yahoo-inc.com