[PATCH proto/x11proto] Adjust <windows.h> wrapping to work with MinGW-w64 headers as well

[Colin Harrison]

Hi,

Jon's patch to Xwindow.h is as far as I get OK at the moment...your extras
cause me problems in a 32-bit build of the xserver.
I'll get back, when I have time, with the reason...quick look...something to
do with the INT64's used in wgl wrappers.

Thanks,
Colin Harrison