Fix compiler warnings in sensorservice.

Bug: 26936282
Change-Id: Ibd43b3c2aaa32cb77b610ca9e1537e5db8827c87
diff --git a/services/sensorservice/Android.mk b/services/sensorservice/Android.mk
index d84ce42..ef17630 100644
--- a/services/sensorservice/Android.mk
+++ b/services/sensorservice/Android.mk
@@ -20,6 +20,8 @@
 
 LOCAL_CFLAGS:= -DLOG_TAG=\"SensorService\"
 
+LOCAL_CFLAGS += -Wall -Werror
+
 LOCAL_CFLAGS += -fvisibility=hidden
 
 LOCAL_SHARED_LIBRARIES := \