garbage C's in server-status and extra child processes with async lingering

close support in Event.  these are set by the listener due to a residual
c->sbh for a worker thread no longer associated with the connection. 

the associated worker threads are really idle and blocked in 
ap_queue_pop_something and will serve new work normally.  but since they
are marked as SERVER_CLOSING rather than SERVER_READY in the scoreboard,
the parent process thinks they are busy and forks extra children.

reproduction recipe: start Event with server-status enabled.  hit
localhost/server-status?refresh=5 and watch the C's trail behind the lone W.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1203708 13f79535-47bb-0310-9956-ffa450edef68