internal/poll: implement RawControl of FD on Windows

This is a followup to https://go-review.googlesource.com/37038.

Updates #19435.

Change-Id: If3d56bca0e8816d1a169f5cf97f27b20695a9955
Reviewed-on: https://go-review.googlesource.com/43692Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/internal/poll/fd_windows.go

@@ -837,7 +837,12 @@ func (fd *FD) GetFileInformationByHandle(data *syscall.ByHandleFileInformation)
 // RawControl invokes the user-defined function f for a non-IO
 // operation.
 func (fd *FD) RawControl(f func(uintptr)) error {
-	return errors.New("not implemented")
+	if err := fd.incref(); err != nil {
+		return err
+	}
+	defer fd.decref()
+	f(uintptr(fd.Sysfd))
+	return nil
 }
 
 // RawRead invokes the user-defined function f for a read operation.