Sensor changes.

1. Some sensors can wake up the AP. Add wakelocks.
2. Handle backward compatibility for rotation vector
   heading accuracy.
3. Cleanup auto disabled sensors.
4. Fix race condition between enable and dispatch.

Change-Id: I39dddf12e208d83cd288201986ee994312555820
diff --git a/services/sensorservice/Android.mk b/services/sensorservice/Android.mk
index a1de3c5..dd698c5 100644
--- a/services/sensorservice/Android.mk
+++ b/services/sensorservice/Android.mk
@@ -20,6 +20,7 @@
 LOCAL_SHARED_LIBRARIES := \
 	libcutils \
 	libhardware \
+	libhardware_legacy \
 	libutils \
 	liblog \
 	libbinder \