add windows stub

Signed-off-by: leongross <[email protected]>

Author: leongross

src/os/file_windows.go

@@ -59,6 +59,10 @@ func Pipe() (r *File, w *File, err error) {
 	return
 }
 
+func (f *file) Truncate(size int64) error {
+	return ErrNotImplemented
+}
+
 func tempDir() string {
 	n := uint32(syscall.MAX_PATH)
 	for {