Halliburton to Restructure KBR Unit  NEW YORK (Reuters) - Halliburton Co. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=HAL.N target=/stocks/quickinfo/fullquote"&gt;HAL.N&lt;/A&gt; on Thursday  said it would restructure its embattled KBR unit and may shed  the business if the oil services company's stock performance  keeps lagging its peers.