Add ApacheOS project to build the OS abstraction libary (in DLL form)

for Win32 systems. This project/makefile also copies the required header(s)
(currently just os.h) to src/main, so must be build *before* any other
project/makefile.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@79189 13f79535-47bb-0310-9956-ffa450edef68