Add cmpxchg_local, cmpxchg64 and cmpxchg64_local to ia64

Add the primitives cmpxchg_local, cmpxchg64 and cmpxchg64_local to ia64. They
use cmpxchg_acq as underlying macro, just like the already existing ia64
cmpxchg().

Changelog:

ia64 cmpxchg_local coding style fix
Quoting Keith Owens:

As a matter of coding style, I prefer

#define cmpxchg_local   cmpxchg
#define cmpxchg64_local cmpxchg64

Which makes it absolutely clear that they are the same code.  With your
patch, humans have to do a string compare of two defines to see if they
are the same.

Note cmpxchg is *not* a performance win vs interrupt disable / enable on IA64.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Acked-by: Christoph Lameter <clameter@sgi.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Keith Owens <kaos@ocs.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>