fix for #2355: discrepancy between std::accumulate and fusion::accumulate

[SVN r57125]

test/functional/unfused.cpp

@@ -57,7 +57,7 @@ struct test_func
         typedef long result_type;
 
         template <typename T>
-        long operator()(T & elem, long value) const
+        long operator()(long value, T & elem) const
         {
           elem += sizeof(T);
           return value + elem;