winnt_mpm: Restore Win32DisableAcceptEx On directive and Win9x platform

by recreating the bucket allocator each time the trans pool is cleared.

PR: 11427 #16 (follow-on)
Submitted by: Tom Donovan <Tom.Donovan acm.org>
Backport: r609181


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.0.x@609184 13f79535-47bb-0310-9956-ffa450edef68