Enable strict warning checks and fix

Change-Id: Id401a937911eb418e93314812f2f7c2b5ecff8d6
diff --git a/services/audioflinger/Android.mk b/services/audioflinger/Android.mk
index 4f826e5..8b831f0 100644
--- a/services/audioflinger/Android.mk
+++ b/services/audioflinger/Android.mk
@@ -14,6 +14,8 @@
     liblog \
     libbinder
 
+LOCAL_CFLAGS := -Wall -Werror
+
 include $(BUILD_SHARED_LIBRARY)
 
 include $(CLEAR_VARS)