AutoZone Earnings Edge Higher  CHICAGO (Reuters) - AutoZone Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=AZO.N target=/stocks/quickinfo/fullquote"&gt;AZO.N&lt;/A&gt;, the largest U.S.  auto parts retailer, on Wednesday said quarterly earnings rose  less than 1 percent as high gas prices made customers choose  between paying for fuel or preventive maintenance.