New POSIX semaphore destruction semantics
Previously, the implementation of POSIX semaphores in *glibc* did not follow the current POSIX requirements for semaphores to be self-synchronizing. As a consequence, the *sem_post()* and *sem_wait()* functions could terminate unexpectedly or return the EINVAL error code because they accessed the semaphore
after it has been destroyed. This update provides an implementation of the new POSIX semaphore destruction semantics which keeps track of waiters, avoiding premature destruction of the semaphore. The semaphores implemented by *glibc* are now self-synchronizing, thus fixing this bug.