Add double bonus for prior countermove fail low
Add a double extra bonus for particularly bad fail low cases. Original idea by Yoshie2000.
STC: https://tests.stockfishchess.org/tests/view/
63a2f0d86b5bf07ac7fad543
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 146488 W: 38992 L: 38532 D: 68964
Ptnml(0-2): 385, 16036, 39965, 16450, 408
LTC: https://tests.stockfishchess.org/tests/view/
63a3eaeb6b5bf07ac7fafdec
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 103992 W: 27853 L: 27423 D: 48716
Ptnml(0-2): 41, 10029, 31435, 10441, 50
closes https://github.com/official-stockfish/Stockfish/pull/4302
Bench:
3801857