net-mgmt/arpwatch: Update to 3.0. Update MASTER_SITES. Add options
for DEBUG (build with debugging support), ETHERCODES (install
ethercodes.dat optionally), and ZEROPAD (zero pad displayed ethernet
addresses by default).

Take maintainership as per pi@ in the PR.

Notable changes since 2.1a15:

• Add -Z (zero pad) and -C (compact) flags to arpwatch and arpsnmp to allow run time selection of zero padded or compact ethernet addresses in arp.dat.
• Check for I/O errors when writing new arp.dat file.
• Add a FreeBSD rc.d startup script.
• Escape unprintable hostnames in arp.dat to avoid corruption.
• Added the -x flag which is like -n but excludes cidrs. Code contributed by Roman Ivanov (awant13@gmail.com).
• Incorporated other fixes and patches with a lot of help from Kurt Jaeger (pi@FreeBSD.org).
• Speed up arp.dat parsing by increasing the size of the hash table.
• Control watcher/watchee from the command line (-w/W flags).

PR: 242346
Approved by: pi (maintainer), ler (mentor, implicit)