testandset on powerpc

[Mark Kettenis]

   From: Andreas Jaeger <aj@suse.de>
   Date: 18 Jul 2000 18:02:09 +0200

   Since testandset is a specialisation it can be optimized - and that
   seems to be the reason why testandset is used here instead of
   compare_and_swap.

   So what's the right thing to do?  

   - Add some define like HAS_TESTANDSET and implement testandset with
     compare_and_swap if testandset is not available?
   - Remove testandset completly?

Please keep testandset.  The i386 has no compare_and_swap, but does
have testandset.

Mark