Count both multi cores and SMP siblings in /proc/cpuinfo siblings.

This avoids breaking user space licensing managers who license by CPU on dual
core systems.

Port of the equivalent code on x86-64.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>