Tweak usage of correction history

Instead of using linear formula use quadratic one. Maximum impact of
correction history is doubled this way, it breaks even with previous
formula on half of maximum value.

Passed STC:
https://tests.stockfishchess.org/tests/view/659591e579aa8af82b95d7e8
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 225216 W: 57616 L: 57019 D: 110581
Ptnml(0-2): 747, 26677, 57201, 27198, 785

Passed LTC:
https://tests.stockfishchess.org/tests/view/6596ee0b79aa8af82b95f08a
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 73314 W: 18524 L: 18125 D: 36665
Ptnml(0-2): 41, 8159, 19875, 8524, 58

closes official-stockfish#4967

Bench: 1464785

src/search.cpp

@@ -745,7 +745,9 @@ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, boo
 
         Value newEval =
           ss->staticEval
-          + thisThread->correctionHistory[us][pawn_structure_index<Correction>(pos)] / 32;
+          + thisThread->correctionHistory[us][pawn_structure_index<Correction>(pos)]
+              * std::abs(thisThread->correctionHistory[us][pawn_structure_index<Correction>(pos)])
+              / 16384;
 
         ss->staticEval = eval = to_static_eval(newEval);
 
@@ -759,7 +761,9 @@ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, boo
 
         Value newEval =
           ss->staticEval
-          + thisThread->correctionHistory[us][pawn_structure_index<Correction>(pos)] / 32;
+          + thisThread->correctionHistory[us][pawn_structure_index<Correction>(pos)]
+              * std::abs(thisThread->correctionHistory[us][pawn_structure_index<Correction>(pos)])
+              / 16384;
 
         ss->staticEval = eval = to_static_eval(newEval);
 
@@ -1502,7 +1506,10 @@ Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {
 
             Value newEval =
               ss->staticEval
-              + thisThread->correctionHistory[us][pawn_structure_index<Correction>(pos)] / 32;
+              + thisThread->correctionHistory[us][pawn_structure_index<Correction>(pos)]
+                  * std::abs(
+                    thisThread->correctionHistory[us][pawn_structure_index<Correction>(pos)])
+                  / 16384;
 
             ss->staticEval = bestValue = to_static_eval(newEval);
 
@@ -1519,7 +1526,10 @@ Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {
 
             Value newEval =
               ss->staticEval
-              + thisThread->correctionHistory[us][pawn_structure_index<Correction>(pos)] / 32;
+              + thisThread->correctionHistory[us][pawn_structure_index<Correction>(pos)]
+                  * std::abs(
+                    thisThread->correctionHistory[us][pawn_structure_index<Correction>(pos)])
+                  / 16384;
 
             ss->staticEval = bestValue = to_static_eval(newEval);
         }