msg external storage is using content_t

src/v2_decoder.cpp

@@ -127,12 +127,12 @@ int zmq::v2_decoder_t::size_ready(uint64_t msg_size, unsigned char const* read_p
         // if the message will be a large message, pass a valid refcnt memory location as well
         rc = in_progress.init ((unsigned char *) read_pos, static_cast <size_t> (msg_size),
                                 shared_message_memory_allocator::call_dec_ref, buffer(),
-                                provide_refcnt ());
+                                provide_content ());
 
         // For small messages, data has been copied and refcount does not have to be increased
         if (in_progress.is_zcmsg())
         {
-            advance_refcnt();
+            advance_content();
             inc_ref();
         }
     }