fix pid numbers in mod_status output when using a threaded mpm. pid_buffer was

being indexed by worker slot during initialization, then by process slot when
generating output.

This saves a little storage and a few cycles, too.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@89534 13f79535-47bb-0310-9956-ffa450edef68