RTLD_LOCAL is not the default on all platforms.
It is important that JNI libraries are not loaded globally to avoid
symbols like JNI_OnLoad_<libname> to be visible in the global scope.

* The polyglot context lock must be acquired to submit a thread local
  action.
* `DeprecationSupport.exit` is called from the `disposeThread` path
  which is called by polyglot while holding the context lock. It is
  synchronized and can lead to code trying to submit a local action.
* To avoid issues, only submit thread local actions while not holding
  the `DeprecationSupport` lock.