broctl status commands should run regardless of lock

[solomon]

broctl should allow the informational commands (top, capstats, netstats, diag, peerstatus, status, et al.) to run without interference from a concurrently locked broctl process. If there is 'broctl cron' or 'broctl start' command runnning, say, from the system crontab, use of broctl to check on the status is often delayed or prevented. Allowing the informational commands to run unimpeded would allow monitoring suites, such as Nagios, to more easily watch the status of the cluster. With the frequent 'cannot get lock' errors, Nagios cannot work with bro & broctl.

[robin]

The problem here is that even the informational commands may rewrite broctl's state file, potentially overwriting what the concurrent Bro process did. We need to change writing of the state file to be depend on any actual changes. That shouldn't be too hard, but will require a bit care to identify cases where it's save to not update the state file.