Don’t score and sort all captures in RECAPTURES stage.

    For these recaptures, we’re are only considering those captures
    that recapture the recapture square (small portion of all the
    captures). Therefore, scoring all of the captures and pick_besting
    out of the whole group is not necessary.

    STC
    LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
    Total: 85583 W: 18978 L: 18983 D: 47622
    http://tests.stockfishchess.org/tests/view/5a717faa0ebc590f2c86e9a7

    LTC
    LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
    Total: 20231 W: 3533 L: 3411 D: 13287
    http://tests.stockfishchess.org/tests/view/5a73ad330ebc5902971a96ba

    Bench: 5023593

src/movepick.cpp

@@ -307,14 +307,13 @@ Move MovePicker::next_move(bool skipQuiets) {
   case QSEARCH_RECAPTURES:
       cur = moves;
       endMoves = generate<CAPTURES>(pos, cur);
-      score<CAPTURES>();
       ++stage;
       /* fallthrough */
 
   case QRECAPTURES:
       while (cur < endMoves)
       {
-          move = pick_best(cur++, endMoves);
+          move = *cur++;
           if (to_sq(move) == recaptureSquare)
               return move;
       }