Count only the most advanced passed pawn for each file.
This patch adjusts definition of passed pawns - if there is a pawn of our color in the same file in front of a current pawn it's no longer counts as passed.
passed STC
https://tests.stockfishchess.org/tests/view/5e802037e42a5c3b3ca2ed07
LLR: 2.94 (-2.94,2.94) {-0.50,1.50}
Total: 215296 W: 41843 L: 41341 D: 132112
Ptnml(0-2): 3688, 25313, 49304, 25495, 3848
passed LTC
https://tests.stockfishchess.org/tests/view/5e806441e42a5c3b3ca2ed2b
LLR: 2.95 (-2.94,2.94) {0.25,1.75}
Total: 74050 W: 9761 L: 9379 D: 54910
Ptnml(0-2): 510, 6838, 22025, 7064, 588
closes https://github.com/official-stockfish/Stockfish/pull/2602
bench: 4902237