RPC_WSTR is not available Visual Studio 2003 or earlier.

(Maybe I should have defined RPC_WSTR on old compiler,
but uuidcreate() is only place using it, so I simply replaced
with unsigned short *)

PC/_msi.c

@@ -18,7 +18,7 @@ static PyObject*
 uuidcreate(PyObject* obj, PyObject*args)
 {
     UUID result;
-    RPC_WSTR cresult;
+    unsigned short *cresult;
     PyObject *oresult;
     
     /* May return ok, local only, and no address.