64bit phobos on Windows?

[dsimcha]

== Quote from Richard Webb (webby at beardmouse.org.uk)'s article
> I know that 64bit support on Windows is behind Linux etc for various reasons,
> but i thought i'd tried building some things with -m64 just to test, and got a
> bunch of errors like
> std\file.d(223): Error: undefined identifier GetLastError
> std\file.d(2067): Error: undefined identifier WIN32_FIND_DATA
> Which appears to be because various things in Phobos use version(Win32), and
> only 'Win64' is set in 64bit builds.
> I guess that at least some of these should be using version(Windows) instead?

Yea, also even if a working Win64 codegen/linker is still fairly far off, it would
be nice to be able to test that code passes semantic analysis in 64 under Windows.