First cut at a file handle cache. It serves on Windows and should work on

Unix systems that implement sendfile.

It is still very rough around the edges (compile warnings, does an unnecessary
stat, not completely Unix friendly, leftover mod_mmap_static code, etc.)


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@85020 13f79535-47bb-0310-9956-ffa450edef68