Provide an option to exclude exact zeros from cancellation reports

[HadrienG2]

I've gotten the chance to experiment with Verrou's new --check-cancellation=yes mode, and I find it very nice and helpful... but a bit prone to false positives on "true" zeroes (e.g. ln(1) or x/x - 1), which typically emerge when the computation is configured to study a certain special case.

Would it be possible to have an option to disable reporting cancellations which return exactly zero? That would eliminate most false positives for me, and if I ever end up on a computation which is actually bad enough to lose all significant bits, there's still the option of flipping the option the other way around in order to study that...