io: io_thr_input(): initialize msg to NULL before entering loop
io: io_thr_input(): initialize msg to NULL before entering loop

    without this initialization, it was possible for the for(;;) loop to
    exit with msg set to an undefined value, which would cause the
    subsequent nmsg_message_destroy() call to dereference an
    uninitialized pointer.

hstern/nmsg,hstern/nmsg,hstern/nmsg,hstern/nmsg,hstern/nmsg