Put bigint branching instrutions in their own BB to not end up in APCs

[leonardoalt]

This is the simplest way of doing this:

• I kept the bigint branching instructions as branching instructions for the sake of basic block detection, so that the instructions after them go to a new BB as target.
• I removed bigint branching instructions from the allow list, which ends up affecting BB detection, but I felt it was safer to keep both flags for these instructions.

I have not tested this with the optimistic precompiles to see if it fixes the bug.