Fix: src.ctf.fs: Using uninitialized value

Fix: src.ctf.fs: Using uninitialized value

`iter_status` may be used uninitialized if the break statement in the
do-while is reached.

Fixes Coverity #1401236:
  CID 1401236 (#1 of 1): Uninitialized scalar variable (UNINIT)
  9. uninit_use: Using uninitialized value iter_status.

Reported-by: Coverity (1401236) Uninitialized scalar variable
Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Change-Id: I96e4608011144cb3c1ae26018d57e98f0358a779
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1261
Reviewed-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>