Fix bug in rarpd:
Fix bug in rarpd:

     Explanation of the bug: when processing its first request, rarpd
     opens a routing socket to send requests to the arp table. It keeps
     that socket open afterwards, while waiting for new RARP requests.

     Meanwhile, the data received on the routing socket fill up until
     they are about 8Kbytes in size. Any additional data is lost.

     When rarpd receives its next RARP request, it tries to access the
     ARP table via a routing socket call, then waits for the answer to
     its own request. This answer is lost because the received data is
     already filled: when looking for the reply, rarpd receives only
     8kbytes worth of data, then loops waiting forever.

     Someone please test it on -STABLE and commit it. We can close the PR
     when testing on STABLE is done.

PR:		bin/5669
Submitted by:	Pierre Beyssac <pb@fasterix.freenix.org>

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