SERVERlistenThread: protect against NULL-pointer
SERVERlistenThread: protect against NULL-pointer

Aparently when the Linux kernel is under stress, it returns a
NULL-pointer for CMSG_FIRSTHDR.  Kind of odd, because how else can you
get an ancilary data structure, if there is nothing?  Instead of
crashing, report the slightly off "unexpected result" message.

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