Fix wrong mate/tb scores from probCut
This fixes returning wrong mated-in scores, or losing a proven mate-in score
from probCut after recent tweaks. The issue reported by @cj5716 on discord.
Passed non-reg STC:
https://tests.stockfishchess.org/tests/view/6583c36b5457644dc9843afe
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 295936 W: 75011 L: 75075 D: 145850
Ptnml(0-2): 978, 33947, 78146, 33955, 942
Passed non-reg LTC:
https://tests.stockfishchess.org/tests/view/658513075457644dc98451cd
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 55932 W: 13970 L: 13786 D: 28176
Ptnml(0-2): 33, 5933, 15837, 6143, 20
closes https://github.com/official-stockfish/Stockfish/pull/4933
Bench: 1308739