This patch introduces the conditional changes required for the three
memory models.  With [patch 1/4] there are three memory models; FLATMEM,
DISCONTIG and SPARSEMEM.  Also a new arch include file sparemem.h is
introduced for defining SPARSEMEM parameters.
Signed-off-by: Bob Picco <bob.picco@hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>