GHSA-w59h-378f-2frm Unsound sending of non-Send types across threads in threadalone

• crates.io threadalone: < 0.2.1 → fixed in 0.2.1

Affected versions can run the `Drop` impl of a non-Send type on a different thread than it was created on. The flaw occurs when a stderr write performed by the `threadalone` crate fails, for example because stderr is redirected to a location on a filesystem that is full, or because stderr is a pipe that has been closed by the reader. Dropping a non-Send type on the wrong thread is unsound. If used with a type such as a pthread-based `MutexGuard`, [the consequence is undefined behavior][mutexguard]. If used with `Rc`, there would be a data race on the reference count, which is likewise undefined behavior. [mutexguard]: https://github.com/rust-lang/rust/issues/23465#issuecomment-82730326