Add windows build notes before any 2.2.X release, which should help

users with the integration notes for obtaining 3rd party db drivers.

This file was shipped in the tarball as a dist artifact, but it
better belongs in the httpd tree to warn users about the first pipe
handling issue if they are rolling their own.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.2.x@782399 13f79535-47bb-0310-9956-ffa450edef68