the package will work by default.
Additionally, setting arpwatch_interfaces in the rc.conf system will
allow you to specify which interfaces arpwatches will run on. By
default (ie, variable empty or not set), it will run on the first
non-local interface it finds.
Approved by: brian (thanks!)
Suggested by: neil.long@materials.oxford.ac.uk (Neil J Long)
Add etc/rc.d/arpwatch.sh
Don't mention arp.dat as an "installed" file - we may want
this after pkg_delete.
