Tidy up the beos mpm by

- removing some unused variables
- correct a problem with pool allocations that killed the server
- add back the ap_lingering close call which I removed in error
  just before going on holiday.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@85568 13f79535-47bb-0310-9956-ffa450edef68