Store the data from accept(2) on the worker->ws, we only need it for
a brief moment until the worker configures a session with it.

If we fail to allocate a session after accepting the connection,
we silently close the connection again:  Presumably it is a DoS
situation.  (false positive:  Extremely popular busy objects)

Make three clearly defined counters for sessions:  Accepted, Dropped
and failed (accept(2) failure).

Lots of spit&polish.