Windows port merge - cachemgr, dnsserver and store_dir changes [PATCH]

Hi,

This is the 4th of some splitted native Windows patches grouped by
functionality.

Native Windows port enhancements:

- Added native Windows support to cachemgr.cc
- Added native Windows support to dnsserver.cc
- On Windows, fork() is not available, so we need to use a workaround in
store_dir.cc for create store directories sequentially

Regards

Guido

-
=======================================================
Serassio Guido
Via Albenga, 11/4 10134 - Torino - ITALY
E-mail: guido.serassio@serassio.it
WWW: http://www.serassio.it