Added close_on_recycle flags for creatin connections.

This flag enables to distinguish between connection types.
Also added a pool cleanup bound to connection pool that recycles
the connection when client disconnects from server.

Submitted by: mturk


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@104599 13f79535-47bb-0310-9956-ffa450edef68