Fix: iterator.c: initialize `status` (may be used uninitialized)

Fix: iterator.c: initialize `status` (may be used uninitialized)

From this GCC warning:

    iterator.c: In function ‘find_message_ge_ns_from_origin’:
    iterator.c:1611:9: error: ‘status’ may be used uninitialized in this
                              function [-Werror=maybe-uninitialized]
     1611 |  return status;
          |

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Change-Id: If6f5f8a63d5a530284a08b9c6dd7f67ecfc9a818
Reviewed-on: https://review.lttng.org/c/babeltrace/+/2120
Tested-by: jenkins <jenkins@lttng.org>
Reviewed-by: Francis Deslauriers <francis.deslauriers@efficios.com>