This dates back to the original copying over from ptp-noposix:
89a46c6d time-wrs/wrs-socket.c: implementation of net functions for wrs arch
(but the bug was not in ptp-noposix).
It is exposed by the newer compiler (well, library) we are using.
But a calloc of 0 bytes should return NULL, to ensure it's not used...
If size is 0, then malloc() returns either NULL, or a unique
pointer value that can later be successfully passed to free().
Signed-off-by: Alessandro Rubini <firstname.lastname@example.org>