perf_counter: Stop open coding unclone_ctx

Instead of open coding the unclone context thingy, put it in
a common function.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
1 file changed