Cleaner null stream initialization

src/utils/PastisOStream.cpp

@@ -7,6 +7,8 @@ PastisOStream pout(std::cout);
 PastisOStream perr(std::cerr);
 
 std::stringstream null_stream;
-const PastisOStream _null_stream_initializer(*[](std::stringstream& null_stream){
+const PastisOStream _null_stream_initializer([]()-> std::stringstream&
+                                             {
                                                null_stream.setstate(std::ios::badbit);
-                                                return &null_stream;}(null_stream));
+                                               return null_stream;
+                                             }());