Fix: remove bad check after epoll wait in consumer

The returned nb_fd value is the number of FD ready for the requested I/O
so having and revents set to 0 is possible since not all fd are ready
thus making this check irrelevant and actually ressource consuming.

Signed-off-by: David Goulet <dgoulet@efficios.com>
Fix: delete the trace directory used for the test

Signed-off-by: David Goulet <dgoulet@efficios.com>