[Sheepdog] [PATCH] configure: add urcu into configure

[Christoph Hellwig]

On Tue, May 08, 2012 at 04:32:16PM +0800, Liu Yuan wrote:
> From: Liu Yuan <tailai.ly at taobao.com>
> 
> It is suppoed to be used by sheepfs. Though sheep doesn't necessarily
> need this library, its well implemented atomic operation header will
> be put good use for other sheep code.
> 
> To use atomic header, just add this in the source:
> 
> #include <urcu/uatomic.h>
> 
> And its API used as uatomic_xxx().

How about switching the zookeeper cluster driver over to it from the
ugly gcc builtins to provide an example?