Change several allocations to behave safely when we're linking 0 interfaces. This also allows xpt_link to be linked against Electric Fence, which will doubtless discover other problems...
Thanks to kherron@sgum.mci.com for the great patch!
git-svn-id: svn://10.0.0.236/trunk@39856 18797224-902f-48f8-a5cc-f745e15eee43
2dc816125c