Fix: relayd: unchecked return values

Fix: relayd: unchecked return values

Coverity reports:
  CID 1171571 (#1 of 1): Unchecked return value (CHECKED_RETURN)
  24. check_return: Calling compat_epoll_add without checking return
  value (as is done elsewhere 11 out of 13 times).

  CID 1171572 (#1 of 1): Unchecked return value (CHECKED_RETURN)
  24. check_return: Calling compat_epoll_add without checking return
  value (as is done elsewhere 11 out of 13 times).

Reported-by: Coverity (1171571) Unchecked return value
Reported-by: Coverity (1171572) Unchecked return value
Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>