logger: add readers waiting on pipe event

logger: add readers waiting on pipe event

when printing logs using dlogutil there was lag
because of default 600ms timeout on epoll_wait
when no new logs were handled dlogutil waited
600ms every time a pipe it was connected with a server
become full

current solution resolves this problem by
adding readers waiting on pipe to the main epoll loop

Change-Id: Idd9c0d26e05b3341c6eef7085c661ffd7683358e