Update best move on fail high

[Aryan1508]

Update current best move on fail-high aspiration searches

LTC
http://chess.grantnet.us/test/12665/

ELO   | 15.78 +- 6.85 (95%)
SPRT  | 40.0+0.40s Threads=1 Hash=64MB
LLR   | 2.95 (-2.94, 2.94) [0.00, 5.00]
GAMES | N: 2864 W: 481 L: 351 D: 2032

STC
http://chess.grantnet.us/test/12663/

ELO   | 12.96 +- 6.65 (95%)
SPRT  | 8.0+0.08s Threads=1 Hash=8MB
LLR   | 3.05 (-2.94, 2.94) [0.00, 5.00]
GAMES | N: 3968 W: 826 L: 678 D: 2464