+
+#if __GNUC__ >= 3
+/* Assume that a flexible array member at the end of a struct
+ * can be defined thus: T arr[]; */
+#define FLEXIBLE_ARRAY
+#else
+/* Assume that it must be defined thus: T arr[0]; */
+#define FLEXIBLE_ARRAY 0
+#endif
+
+#if defined(SMP) || defined(THREADED_RTS)
+#define RTS_SUPPORTS_THREADS 1