CG: propagate XACK by incrementing server.dirty.

This should be more than enough, even if in case of partial IDs that are
not found, we send all the IDs to the slave/AOF, but this is definitely
a corner case without bad effects if not some wasted space.

src/t_stream.c

@@ -1559,6 +1559,7 @@ void xackCommand(client *c) {
             raxRemove(nack->consumer->pel,buf,sizeof(buf),NULL);
             streamFreeNACK(nack);
             acknowledged++;
+            server.dirty++;
         }
     }
     addReplyLongLong(c,acknowledged);