Avoid 'double assigments' tricks

Bitboard init code is already noteasy to follow,
so don't make it even harder using 'smart' code.

Also reindent a while loop in standard way.

No functional change.
Retire FakeSplit

    - Currently broken
    - Never been really useful
    - Does not work well with new splitting model

Verified for no regression at STC with 3 threads:
LLR: 2.96 (-2.94,2.94) [-6.00,0.00]
Total: 81905 W: 12122 L: 12381 D: 57402

No functional change