x86: fix stack overflow for large values of MAX_APICS

physid_mask_of_physid() causes a huge stack (12k) to be created if the
number of APICS is large. Replace physid_mask_of_physid() with a
new function that does not create large stacks. This is a problem only
on large x86_64 systems.

this paves the way to increase MAX_APICS.

Signed-off-by: Jack Steiner <steiner@sgi.com>
Cc: linux-mm@kvack.org
Cc: mingo@elte.hu
Cc: tglx@linutronix.de
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --cc arch/x86/kernel/apic_32.c
Simple merge

diff --cc arch/x86/kernel/apic_64.c
Simple merge

diff --cc arch/x86/kernel/smpboot.c
Simple merge

diff --cc include/asm-x86/mpspec.h
Simple merge