consistenttime SIGILL due to FFI unwind

[Mark-Simulacrum]

https://crater-reports.s3.amazonaws.com/beta-1.33-1/beta-2019-01-22/reg/consistenttime-0.2.0/log.txt

This is due to #55982.

cc @valarauca

I am immediately closing this as this is an intended behavior change.

[Mark-Simulacrum]

https://crater-reports.s3.amazonaws.com/beta-1.33-1/beta-2019-01-22/reg/mujs-0.0.3/log.txt seems likely to be a similar case, though have not determined that for sure. cc @hean01