Until https://github.com/rust-lang/rust/issues/52652 is fixed,
unwinding on panic is potentially unsound in a mixed C/Rust codebase.
The codebase is supposed to be panic-free already, but just to be safe.
This started mattering at commit d1820c1516a31a149fc51a9e5126bf899e4c4e08.
Fixes #27199; bugfix on tor-0.3.3.1-alpha.