Enable strict warnings and fix unused warnings

Test: builds without warnings
Change-Id: I0701a44cbd9a2adc405a1e253b57df7ee03a90b7
diff --git a/media/libeffects/lvm/lib/Android.mk b/media/libeffects/lvm/lib/Android.mk
index bb56c75..afc87bb 100644
--- a/media/libeffects/lvm/lib/Android.mk
+++ b/media/libeffects/lvm/lib/Android.mk
@@ -120,6 +120,7 @@
     $(LOCAL_PATH)/StereoWidening/lib
 
 LOCAL_CFLAGS += -fvisibility=hidden
+LOCAL_CFLAGS += -Wall -Werror
 
 include $(BUILD_STATIC_LIBRARY)
 
@@ -177,4 +178,5 @@
     $(LOCAL_PATH)/Common/src
 
 LOCAL_CFLAGS += -fvisibility=hidden
+LOCAL_CFLAGS += -Wall -Werror
 include $(BUILD_STATIC_LIBRARY)