View source for c/thread/tss delete

===Notes===
The POSIX equivalent of this function is [http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_key_delete.html {{tt|pthread_key_delete}}].

The reason {{tt|tss_delete}} never calls destructors is that the destructors (called at thread exit) are normally intended to be executed by the same thread that originally set the value (via {{lc|tss_set}}) that the destructor will be dealing with, and may even rely on the values of that or other thread-specific data as seen by that thread. The thread executing {{tt|tss_delete}} has no access to other threads' TSS. Even if it were possible to call the destructor for each thread's own value associated with {{tt|tss_id}}, {{tt|tss_delete}} would have to synchronize with every thread if only to examine whether the value of this TSS in that thread is null (destructors are only called against non-null values).