util/u_queue: really use futex-based fences

The relevant define changed in the final revision of the simple mutex
patch.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
diff --git a/src/util/u_queue.h b/src/util/u_queue.h
index 57753bd..d49f713 100644
--- a/src/util/u_queue.h
+++ b/src/util/u_queue.h
@@ -49,7 +49,7 @@
 #define UTIL_QUEUE_INIT_USE_MINIMUM_PRIORITY      (1 << 0)
 #define UTIL_QUEUE_INIT_RESIZE_IF_FULL            (1 << 1)
 
-#if defined(__GNUC__) && defined(HAVE_FUTEX)
+#if defined(__GNUC__) && defined(HAVE_LINUX_FUTEX_H)
 #define UTIL_QUEUE_FENCE_FUTEX
 #else
 #define UTIL_QUEUE_FENCE_STANDARD