Changeset 1b1be254 in rtems for cpukit/score

score: Thread life cycle re-implementation

The thread deletion is now supported on SMP.

This change fixes the following PRs:

PR1814: SMP race condition between stack free and dispatch

PR2035: psxcancel reveals NULL pointer access in _Thread_queue_Extract()

The POSIX cleanup handler are now called in the right context (should be
called in the context of the terminating thread).

​http://pubs.opengroup.org/onlinepubs/009695399/functions/xsh_chap02_09.html

Add a user extension the reflects a thread termination event. This is
used to reclaim the Newlib reentrancy structure (may use file
operations), the POSIX cleanup handlers and the POSIX key destructors.