Avoid requiredTwos duplication.
Avoid requiredTwos duplication.

This was being computed identically on both sides of a branch (without
any variables being modified in between), so it can be lifted up,
and a RYU_DEBUG line can be uncommented. The scope ends immediately
afterwards.

ulfjack/ryu,ulfjack/ryu,ulfjack/ryu,ulfjack/ryu