Halliburton Says It May Separate 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; said on  Thursday it would restructure its KBR unit and may shed the  business if the company's stock performance continues to lag  behind peers.