Corrects two issues. 012139638d
added a dec-ref in the status==EPERM path, but neglected to
add a matching inc-ref. So if a joinable pthread_create()
actually errored with EPERM, then no reference is left for the
joiner.
Secondly, and far more suble, is a data race if pthread_create()
succeeds in starting a new thread, which ends and free()'s
pthreadInfo before pthread_create() writes pthreadInfo->tid .
214b5d935b