[PATCH] perf_counter/powerpc: Fix compilation after perf_counter_overflow change

[Paul Mackerras]

Ingo Molnar writes:

> Paul, you might also want to test the perfcounter bits of -tip on 
> PowerPC a bit more frequently - this patch was there for 5 days before i 
> sent it to Linus.

Yes, I'll try to do that in future.

I hope I didn't come across as blaming anyone for anything - that
wasn't my intention at all.

> Cross-builds didnt catch it as perfcounters isnt enabled by default in 
> any of the powerpc defconfigs:

I'll get that fixed too.

Paul.