title: Change target of symlink without deletion
body: <p>Is it possible to change contents of symlink using <code>Qt</code>?</p>
  
  <p>Static <code>QFile::link</code> and non-static one both return <code>false</code> if linkname filepath is already exist.</p>
  
  <p>I just want to retarget symlink. An analogue of <code>ln -sf</code>, but crossplatform.</p>