Small Major/Minor piece key simplification/optimization.

closes #5710

No functional change

src/position.cpp

@@ -360,7 +360,7 @@ void Position::set_state() const {
             {
                 st->nonPawnMaterial[color_of(pc)] += PieceValue[pc];
 
-                if (type_of(pc) == QUEEN || type_of(pc) == ROOK)
+                if (type_of(pc) >= ROOK)
                     st->majorPieceKey ^= Zobrist::psq[pc][s];
 
                 else
@@ -759,7 +759,7 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
             st->nonPawnMaterial[them] -= PieceValue[captured];
             st->nonPawnKey[them] ^= Zobrist::psq[captured][capsq];
 
-            if (type_of(captured) == QUEEN || type_of(captured) == ROOK)
+            if (type_of(captured) >= ROOK)
                 st->majorPieceKey ^= Zobrist::psq[captured][capsq];
 
             else
@@ -844,7 +844,7 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
             st->materialKey ^=
               Zobrist::psq[promotion][pieceCount[promotion] - 1] ^ Zobrist::psq[pc][pieceCount[pc]];
 
-            if (promotionType == QUEEN || promotionType == ROOK)
+            if (promotionType >= ROOK)
                 st->majorPieceKey ^= Zobrist::psq[promotion][to];
 
             else
@@ -871,7 +871,7 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
             st->minorPieceKey ^= Zobrist::psq[pc][from] ^ Zobrist::psq[pc][to];
         }
 
-        else if (type_of(pc) == QUEEN || type_of(pc) == ROOK)
+        else if (type_of(pc) >= ROOK)
             st->majorPieceKey ^= Zobrist::psq[pc][from] ^ Zobrist::psq[pc][to];
 
         else