AWS-LC registers an `atexit` handler that intentionally acquires a lock
without releasing it. AWS-LC also has `thread_local` objects which
acquire this lock in their destructor. Destructors for `thread_local`s
run under the loader lock. So, there is a race condition where, if a
thread exits after `atexit` handlers have run, the TLS destructors will
block indefinitely on this lock while holding the loader lock. Since
`ExitProcess` also requires the loader lock, process teardown will
deadlock.
Closes#54856
Release Notes:
- Fixed an issue where the Zed process wouldn't exit after closing all
windows
John Tur
067ec60e1a