Disable (again) futex ReaderWriterMutex implementation.

Change-Id: Ia7cfb18dfd3d7691c6cd2ba27d91f484e82c92db
diff --git a/src/mutex.h b/src/mutex.h
index f69eb32..32aeaf9 100644
--- a/src/mutex.h
+++ b/src/mutex.h
@@ -31,7 +31,7 @@
 #if defined(__APPLE__)
 #define ART_USE_FUTEXES 0
 #else
-#define ART_USE_FUTEXES 1
+#define ART_USE_FUTEXES 0
 #endif
 
 // Currently Darwin doesn't support locks with timeouts.