Drop support for Windows 2000; allow any XP API (but not Vista+). Drop SDK version configuration for Tk compilation, to not bind it to W2k anymore. Binding it to XP would conflict with Tk's own binding of tkMenu to W2k.

#include "Python.h"

#ifndef PLATFORM
#define PLATFORM "unknown"
#endif

const char *
Py_GetPlatform(void)
{
	return PLATFORM;
}