Andrew Dunstan: First cuckoo in spring

I'm not sure if I am the first person who has produced a fully working 64 bit Postgres for Windows, but I haven't heard of anyone else doing it, and that's what I did today using MSys and the Mingw64 toolchain on my 64 bit Windows 7 machine. Tomorrow I'll create a git branch for tracking this work andf push it to github.

We probably need to start talking about our use of the term "win32" ... it could get badly misleading and confusing.