perf: Ensure swevent hrtimer is properly destroyed

perf: Ensure swevent hrtimer is properly destroyed

With the change to hrtimer_try_to_cancel() in
perf_swevent_cancel_hrtimer() it appears possible for the hrtimer to
still be active by the time the event gets freed.

Make sure the event does a full hrtimer_cancel() on the free path by
installing a perf_event::destroy handler.

Fixes: eb3182ef0405 ("perf/core: Fix system hang caused by cpu-clock usage")
Reported-by: CyberUnicorns <a101e_iotvul@163.com>
Tested-by: CyberUnicorns <a101e_iotvul@163.com>
Debugged-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>