Fix: consumer fd recv thread should write into non-blocking pipe

Fix: consumer fd recv thread should write into non-blocking pipe

Writing into a blocking pipe will cause the writer thread to block on
the poll fds thread when the pipe is full. Given that we would like to
batch stream array reallocation as much as possible, this wakeup should
not block.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>