ANDROID: GKI: perf: Add field for struct perf_event

Adds the new struct variable "readable_on_cpus" to reduce the ABI
diff. The Full feature is under commit f994cb43aa ("perf/core:
Add support for PMUs that can be read from more than 1 CPU").

Bug: 148872640
Test: compile test
(cherry picked from commit f994cb43aa)
[Only cherry-picked the ABI difference]
Signed-off-by: Will McVicker <willmcvicker@google.com>
Change-Id: If46a71163efde2245e955b23da58550e21082e62

include/linux/perf_event.h

@@ -648,6 +648,7 @@ struct perf_event {
 
 	int				oncpu;
 	int				cpu;
+	cpumask_t			readable_on_cpus;
 
 	struct list_head		owner_entry;
 	struct task_struct		*owner;