fixing issue LeelaChessZero#2003

node_limits value now follows the value passed to the stopper in common.cc (= 4000000000 if params.nodes was not initialized, = params.nodes if params.nodes was initialized to an int, 0 included)

src/mcts/stoppers/stoppers.h

@@ -54,7 +54,7 @@ class ChainedSearchStopper : public SearchStopper {
 class VisitsStopper : public SearchStopper {
  public:
   VisitsStopper(int64_t limit, bool populate_remaining_playouts)
-    : nodes_limit_(limit ? limit : 4000000000ll),
+    : nodes_limit_(limit),
         populate_remaining_playouts_(populate_remaining_playouts) {}
   int64_t GetVisitsLimit() const { return nodes_limit_; }
   bool ShouldStop(const IterationStats&, StoppersHints*) override;