Advisories for Cargo/Internment package

ArcIntern::drop has a race condition where it can release memory which is about to get another user. The new user will get a reference to freed memory. This was fixed by serializing access to an interned object while it is being deallocated. Versions prior to 0.3.12 used stronger locking which avoided the problem.

An issue was discovered in the internment crate before 0.4.2 for Rust. There is a data race that can cause memory corruption because of the unconditional implementation of Sync for Intern.