libutils: turn on -Werror

- Deal with some -Wunused issues
- Override PRI macros (windows)
- Revert use of PRI macros on off64_t (linux)
- Deal with a gnu++11 complaince issue

Change-Id: Ie66751293bd84477a5a6dfd8a57e700a16e36964
diff --git a/libutils/StopWatch.cpp b/libutils/StopWatch.cpp
index b1708d6..8c7b596 100644
--- a/libutils/StopWatch.cpp
+++ b/libutils/StopWatch.cpp
@@ -21,7 +21,9 @@
 #include <stdio.h>
 
 /* for PRId64 */
+#ifndef __STDC_FORMAT_MACROS
 #define __STDC_FORMAT_MACROS 1
+#endif
 #include <inttypes.h>
 
 #include <utils/Log.h>