Tweak threat evaluation for losing chess variants

Tweak threat evaluation for losing chess variants

giveaway STC
LLR: 2.97 (-2.94,2.94) [0.00,10.00]
Total: 5279 W: 2193 L: 2034 D: 1052
http://35.161.250.236:6543/tests/view/5cb197406e23db76ed2526e8

giveaway LTC
LLR: 2.95 (-2.94,2.94) [0.00,10.00]
Total: 23616 W: 9228 L: 8824 D: 5564
http://35.161.250.236:6543/tests/view/5cb2c5fe6e23db76ed252702

losers STC (failed)
LLR: -2.97 (-2.94,2.94) [-10.00,5.00]
Total: 7179 W: 3195 L: 3309 D: 675
http://35.161.250.236:6543/tests/view/5cb197556e23db76ed2526eb

losers LTC
LLR: 2.98 (-2.94,2.94) [-10.00,5.00]
Total: 2363 W: 1066 L: 1021 D: 276
http://35.161.250.236:6543/tests/view/5cb2c60b6e23db76ed252704