For services explicitly configured as lazy, SystemServer will now listen
on the socket and only spawn the service once a client attempts to connect
to the socket.
When reaping a child, SystemServer will now match up child's pid with its own
record of the services, and respawn the service if keepalive is enabled for it.
For example, we want to restart the WindowServer if it crashes, but we wouldn't
want to restart the Terminal if it gets closed.
