liblog: set -Werror

- Deal with some -Wunused issues
- Cleanup UNUSED to __unused transition

Change-Id: Icd33808d4c974625f4fd0a126a90a2b4c90c8314
diff --git a/liblog/tests/liblog_test.cpp b/liblog/tests/liblog_test.cpp
index c6f981f..ec35e45 100644
--- a/liblog/tests/liblog_test.cpp
+++ b/liblog/tests/liblog_test.cpp
@@ -164,7 +164,7 @@
 static unsigned signaled;
 log_time signal_time;
 
-static void caught_blocking(int signum)
+static void caught_blocking(int /*signum*/)
 {
     unsigned long long v = 0xDEADBEEFA55A0000ULL;