logd: turn on -Werror

- Deal with some -Wunused / -Wunused-variable issues

Change-Id: Ic86cd7b0680868ad0536198b71a34cb19134fc21
diff --git a/logd/Android.mk b/logd/Android.mk
index 0235478..9f4c64f 100644
--- a/logd/Android.mk
+++ b/logd/Android.mk
@@ -25,7 +25,7 @@
     libcutils \
     libutils
 
-LOCAL_MODULE_TAGS := optional
+LOCAL_CFLAGS := -Werror
 
 include $(BUILD_EXECUTABLE)