add <utility> to be include order agnostic

DennisOSRM · DennisOSRM · commit 9be8c519c67e · 2014-05-26T16:51:38.000+02:00
diff --git a/recursive_wrapper.hpp b/recursive_wrapper.hpp
@@ -1,6 +1,8 @@
 #ifndef UTIL_VARIANT_RECURSIVE_WRAPPER_HPP
 #define UTIL_VARIANT_RECURSIVE_WRAPPER_HPP
 
+#include <utility>
+
 namespace util {
 
 template <typename T>
