Patch from Martin Bligh.  It should only affect machines using
discontigmem.

"This patch cleans up free_area_init stuff, and undefines mem_map and
max_mapnr for discontigmem, where they were horrible kludges anyway
...  We just use the lmem_maps instead, which makes much more sense.
It also kills pgdat->node_start_mapnr, which is tarred with the same
brush.

It breaks free_area_init_core into a couple of sections, pulls the
allocation of the lmem_map back into the next higher function, and
passes more things via the pgdat.  But that's not very interesting,
the objective was to kill mem_map for discontigmem, which seems to
attract bugs like flypaper.  This brings any misuses to obvious
compile-time errors rather than wierd oopses, which I can't help but
feel is a good thing.

It does break other discontigmem architectures, but in a very obvious
way (they won't compile) and it's easy to fix.  I think that's a small
price to pay ...  ;-) At some point soon I will follow up with a patch
to remove free_area_init_node for the contig mem case, or at the very
least rename it to something more sensible, like __free_area_init.

Christoph has grander plans to kill mem_map more extensively in
addition to the attatched, but I've heard nobody disagree that it
should die for the discontigmem case at least.

Oh, and I renamed mem_map in drivers/pcmcia/sa1100 to pc_mem_map
because my tiny little brain (and cscope) find it confusing like that.

Tested on 16-way NUMA-Q with discontigmem + NUMA support and on a
standard PC (well, boots and appears functional).  On top of
2.5.33-mm4"