Simplify SEE threshold (#408)

Elo | 1.10 +- 2.00 (95%)
SPRT | 40.0+0.40s Threads=1 Hash=64MB
LLR | 2.97 (-2.94, 2.94) [-3.00, 1.00]
Games | N: 27446 W: 5893 L: 5806 D: 15747
Penta | [14, 3157, 7295, 3242, 15]

Bench: 6519222

src/movepicker.cpp

@@ -98,7 +98,7 @@ int NextMove(Movepicker* mp, const bool skip) {
             partialInsertionSort(&mp->moveList, mp->idx);
             const int move = mp->moveList.moves[mp->idx].move;
             const int score = mp->moveList.moves[mp->idx].score;
-            const int SEEThreshold = mp->movepickerType == SEARCH ? -score / 64 : -108;
+            const int SEEThreshold = -score / 64;
             ++mp->idx;
             if (move == mp->ttMove)
                 continue;

src/search.cpp

@@ -632,7 +632,7 @@ int Negamax(int alpha, int beta, int depth, const bool cutNode, ThreadData* td,
 
         // increment nodes count
         info->nodes++;
-        uint64_t nodesBeforeSearch = info->nodes;
+        const uint64_t nodesBeforeSearch = info->nodes;
         // Conditions to consider LMR. Calculate how much we should reduce the search depth.
         if (totalMoves > 1 + pvNode && depth >= 3 && (isQuiet || !ttPv)) {