make all libsurfaceflinger and libsensorservice symbols's visibility hidden

we only export the main entry-point.
this saves about 150KB.

Change-Id: I55eb2b6705386fdfa43860deb62f9cdd2a0982aa
diff --git a/services/sensorservice/Android.mk b/services/sensorservice/Android.mk
index dd698c5..14a4e55 100644
--- a/services/sensorservice/Android.mk
+++ b/services/sensorservice/Android.mk
@@ -12,11 +12,12 @@
     SensorDevice.cpp \
     SensorFusion.cpp \
     SensorInterface.cpp \
-    SensorService.cpp \
-
+    SensorService.cpp
 
 LOCAL_CFLAGS:= -DLOG_TAG=\"SensorService\"
 
+LOCAL_CFLAGS += -fvisibility=hidden
+
 LOCAL_SHARED_LIBRARIES := \
 	libcutils \
 	libhardware \
@@ -27,8 +28,6 @@
 	libui \
 	libgui
 
-
-
 LOCAL_MODULE:= libsensorservice
 
 include $(BUILD_SHARED_LIBRARY)