Allow for modules to keep track of worker slot

numbers themselves if they want, by allowing for
worker create/alloc functions to take a slot number id.
Done via _wid() variants of 3 proxy funcs.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@964089 13f79535-47bb-0310-9956-ffa450edef68