If a thread is joined using `pthread_join()`, then the
internal state would be set to `PTHREAD_EXITED`.
Previously, `pthread_create()` would only consider pthreads
with internal state `PTHREAD_TERMINATED` as candidates for new
threads. However, that causes a descriptor leak.
We should be able to reuse a single thread an infinite number
of times.
Here, we also consider threads with internal state
`PTHREAD_EXITED` as candiates in `pthread_create()`.
Fixes#47609
Signed-off-by: Christopher Friedt <cfriedt@fb.com>
da0398d198