Amazon Posts Profit, Shares Fall  SAN FRANCISCO (Reuters) - Amazon.com Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=AMZN.O target=/stocks/quickinfo/fullquote"&gt;AMZN.O&lt;/A&gt; on  Thursday posted a higher quarterly profit on strong  international sales but its stock fell more than 4 percent as  the results from the online retailer failed to top Wall Street  expectations.