Add more SP_ constants

Change-Id: I52c8ea33b9b915fc08546f2ca0b191391f58506b
diff --git a/include/cutils/sched_policy.h b/include/cutils/sched_policy.h
index c6e4fc4..ba84ce3 100644
--- a/include/cutils/sched_policy.h
+++ b/include/cutils/sched_policy.h
@@ -26,6 +26,9 @@
     SP_DEFAULT    = -1,
     SP_BACKGROUND = 0,
     SP_FOREGROUND = 1,
+    SP_SYSTEM     = 2,  // can't be used with set_sched_policy()
+    SP_AUDIO_APP  = 3,
+    SP_AUDIO_SYS  = 4,
     SP_CNT,
     SP_MAX        = SP_CNT - 1,
     SP_SYSTEM_DEFAULT = SP_FOREGROUND,