arp_update_entry(). While arp_timer() was sending the last request
arp_update_entry() could be called (caused by an incoming reply) and
free the request buffer, which arp_timer() would free a moment later
again. The problem is not completely solved, since a duplicate reply can
still cause a double free. Checked in mainly for Axel's reading
pleasure. :-)
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@25252 a95241bf-73f2-0310-859d-f6bbb57e9c96