[cairo] Cairo and GdiPlus or two win32 backends

[Stuart Parmenter]

I'd like to pipe up here and say that I like Owen's approach is the
one I'm supporting and plan to help optimize in my "free time".  I'm
fine with removing the GDI+ backend from CVS.

It is going to be important that we're able to build cairo on windows
with visual studio (which isn't really that hard), but someone else
can probably tackle that problem.

stuart