Use -Werror in packages/inputmethods/LatinIME/native/jni

* Suppress warning on unused loop index variable.

Bug: 66996870
Test: build with WITH_TIDY=1
Change-Id: Ia3f0f9cc4cb0ebeeac9b1ff51955597a725c87ef
diff --git a/native/jni/Android.mk b/native/jni/Android.mk
index 01b32a9..5384648 100644
--- a/native/jni/Android.mk
+++ b/native/jni/Android.mk
@@ -88,6 +88,7 @@
 
 LOCAL_SDK_VERSION := 14
 LOCAL_NDK_STL_VARIANT := c++_static
+LOCAL_CFLAGS := -Wall -Werror
 LOCAL_LDFLAGS += -ldl
 
 include $(BUILD_SHARED_LIBRARY)
@@ -99,3 +100,4 @@
 
 #################### Unit test on target environment
 include $(LOCAL_PATH)/TargetUnitTests.mk
+//LOCAL_CFLAGS += -Wall -Werror