Fix critical SEE bug
It is somewhat unbilievable but our SEE is broken !
If the first SEE move is a king capture and square is
defended then SEE continues instead of breaking.
The bug shows only on normal SEE, not see_sign() so
probing with a:
dbg_hit_on_c(slIndex==1, captured == KING);
reports just a tiny:
Total 3465656 Hits 6646 hit rate (%) 0
Bug was there since 351ef5c85b6d4b9c71e9da of 26/6/2011 (!)
although for some reason didn't show immediately, indeed the
bougous patch was a "No functional change" (!!)
bench: 4793754