atrace: trace binder_set_priority.

Useful to debug priority inheritance issues.

Test: binder_set_priority events traced
Change-Id: I89d6ad463aa670ce9b838cb051e58d58e80f07f6
diff --git a/cmds/atrace/atrace.cpp b/cmds/atrace/atrace.cpp
index 457d203..4d18408 100644
--- a/cmds/atrace/atrace.cpp
+++ b/cmds/atrace/atrace.cpp
@@ -181,6 +181,7 @@
     { "binder_driver", "Binder Kernel driver", 0, {
         { REQ,      "events/binder/binder_transaction/enable" },
         { REQ,      "events/binder/binder_transaction_received/enable" },
+        { OPT,      "events/binder/binder_set_priority/enable" },
     } },
     { "binder_lock", "Binder global lock trace", 0, {
         { OPT,      "events/binder/binder_lock/enable" },