[IA64] Itanium Spec updates

Updates based on the "Intel® Itanium® Architecture Software Developer's Manual
Specification Update October 2007".

http://download.intel.com/design/itanium/specupdt/24869911.pdf



Signed-off-by: Russ Anderson <rja@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>