This fixes the bug that caused BUG_ON(!irqs_disabled()) to trigger in
run_posix_cpu_timers() on alpha/smp. We didn't disable interrupts
properly before calling smp_percpu_timer_interrupt().
We *do* disable interrupts everywhere except this unfortunate
smp_percpu_timer_interrupt(). Fixed thus.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>