Revert "Store moves sent with "position" UCI command"

This reverts commit 0d68b523a3.

After easy move semplification this machinery is not
needed anymore (because of we don't need to know if a
root move is a recapture)

No functional change.

src/benchmark.cpp

@@ -114,7 +114,6 @@ void benchmark(const Position& current, istream& is) {
 
   int64_t nodes = 0;
   Search::StateStackPtr st;
-  Search::MovesVectPtr mv;
   Time::point elapsed = Time::now();
 
   for (size_t i = 0; i < fens.size(); i++)
@@ -131,7 +130,7 @@ void benchmark(const Position& current, istream& is) {
       }
       else
       {
-          Threads.start_thinking(pos, limits, vector<Move>(), st, mv);
+          Threads.start_thinking(pos, limits, vector<Move>(), st);
           Threads.wait_for_think_finished();
           nodes += Search::RootPos.nodes_searched();
       }