Set the return value of rmw_ret_t before entering the loop. (#171)
Set the return value of rmw_ret_t before entering the loop. (#171)

clang static analysis pointed out that if we never did *any*
iterations of the loop in SLEEP_AND_RETRY_UNTIL, then we
would be comparing an uninitialized value of rmw_ret_t with
RMW_RET_OK.  Just set it to RMW_RET_ERROR in this unlikely
case which will cause us to fail the test.

Signed-off-by: Chris Lalancette <281cd07d7578d97c83271fbbf2faddb83ab3791c@openrobotics.org>
ros2/rmw_implementation,ros2/rmw_implementation