against 2.6.12-rc4

This patch adds dumping of calltraces on _all_ CPUs
on AltSysRq-P and NMI LOCKUP. It does this via sending
NMI IPI interrupts to the cpus.

I saw the same patch in RedHat kernels, here goes our own version of the 
patch, not sure it will be accepted, but I think it can be used by some 
people at least for debugging lockups etc.

Signed-Off-By: Kirill Korotaev <dev@sw.ru>
Signed-Off-By: Pavel Emelianov <xemul@sw.ru>

Kirill