perf: Fixup SIGTRAP and sample_flags interaction

The perf_event_attr::sigtrap functionality relies on data->addr being
set. However commit 7b0846301531 ("perf: Use sample_flags for addr")
changed this to only initialize data->addr when not 0.

Fixes: 7b0846301531 ("perf: Use sample_flags for addr")
Signed-off-by: Peter Zijlstra (Intel) <[e-mail]>
Link: https://lkml.kernel.org/r/Y3426b4OimE%2FI5po%40hirez.programming.kicks-ass.net

kernel/events/core.c

···
 			 */
 			WARN_ON_ONCE(event->pending_sigtrap != pending_id);
 		}
-		event->pending_addr = data->addr;
+
+		event->pending_addr = 0;
+		if (data->sample_flags & PERF_SAMPLE_ADDR)
+			event->pending_addr = data->addr;
 		irq_work_queue(&event->pending_irq);
 	}