Enable strict warning checks and fix

Change-Id: Id401a937911eb418e93314812f2f7c2b5ecff8d6
diff --git a/media/ndk/Android.mk b/media/ndk/Android.mk
index 7f6b66b..74729e4 100644
--- a/media/ndk/Android.mk
+++ b/media/ndk/Android.mk
@@ -40,7 +40,7 @@
 
 LOCAL_CFLAGS += -fvisibility=hidden -D EXPORT='__attribute__ ((visibility ("default")))'
 
-LOCAL_CFLAGS += -Werror
+LOCAL_CFLAGS += -Werror -Wall
 
 LOCAL_SHARED_LIBRARIES := \
     libbinder \