Use the route that's guaranteed to exist when picking a source address for ARP requests.
Use the route that's guaranteed to exist when picking a source address
for ARP requests.

The NetBSD version of this patch (see NetBSD PR kern/2381) has this change
already.  This should close our PR kern/1140 .

Although it's not quite what he submitted, I got the idea from him so
Submitted by:	Jin Guojun <jin@george.lbl.gov>

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase