Fixing a memory leak with the threads bucket_allocator. We were allocating

too much and not freeing up enough.  On a thread exit the bucket and the
transaction pool need to be cleaned up.  When the MPM exits, the main pool
needs to be cleaned up.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@95207 13f79535-47bb-0310-9956-ffa450edef68