disabling wow64, testing 64-bit wine-mono P/invoke

[Vincent Povirk]

> I was very confused by both of
> libmono-2.0-x86_64.dll  libmono-2.0-x86.dll  MonoPosixHelper-x86_64.dll  MonoPosixHelper-x86.dll
> in c:/windows/mono/mono-2.0/bin/
>
> In fact libmono-2.0-x86_64.dll MonoPosixHelper-x86_64.dll
> are never used, at the moment.

Correct. Alexandre insisted we include 64-bit builds anyway. In
theory, they would work if Wine had everything required.