set /proc/sys/net/unix/max_dgram_qlen to large value

- init: set /proc/sys/net/unix/max_dgram_qlen to 300
- libsysutils: Add listen backlog argument to startListener
- logd: set listen backlog to 300

Change-Id: Id6d37d6c937ba2d221e76258d89c9516619caeec
4 files changed