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.
Merge branch 'master' of https://github.com/official-stockfish/Stockfish
Merge branch 'master' of https://github.com/lantonov/Stockfish