[Bug-XBoard] Winboard Analysis of mate

[Phil Musk]

When trying to analyse eg:

4r3/1pp4k/p2pP1pp/3P1p2/1P3P1q/2N4P/P2QRb1K/8 b - - 0 29

via Crafty, nothing is displayed. Mate is (quickly) found so Crafty ends its
work, but Winboard doesn't refresh the display.

This also happens in general when analysing and mate is found - the Winboard
display is not refreshed.

Thanks for what is a GREAT piece of S/W,

Phil