Single byte Atomic::cmpxchg implementation

[Andrew Haley]

On 09/11/2014 11:34 AM, David Holmes wrote:
> For things like Atomic::*  the definitions are in platform specific 
> files so you should be able to use whatever mechanism you want and 
> require whatever minimal compiler version is needed.

But they're not: Atomic::cmpxchg(jbyte seems to be defined in common
code.  If it was defined in a platform-specific file there would be no
problem for us to discuss in this thread.

Andrew.