Upon startup, as Bro is loading its bro scripts, it fails to close each file,
resulting in too many open files.
As a result, on OS X it is necessary to use the "ulimit -n" command
to increase the allowed number of open files. Otherwise, bro
will fail upon startup with errors like this:
error in /Users/bro/test/share/bro/policy/frameworks/control/controllee.bro, line 13: Failed to open file /Users/bro/test/share/bro/policy/frameworks/control/controllee.bro: Too many open files