> The path which sets "pthread_version" should be inside "#ifdef
> _POSIX_THREADS".
> Also, some comments about the doc:
> - you need a "versionadded" tag

Right, fixed.

> - "use_semaphores" should explain that these semaphores are used for
> locks; also the alternative is "use mutexes and condition variables",
> not "use mutexes"

Hum, a boolean was not a good idea. I replaced this key by:

 * 'lock' (string): name of the lock implementation

   * 'semaphore': a lock uses a semaphore
   * 'mutex+cond': a lock uses a mutex and a condition variable

I also renamed 'name' key to 'thread', so 'thread' is the name of the
*thread* implementation, and 'lock' is the name of the *lock*
implementation.

For example, test_threadsignals now uses:
-----------
USING_PTHREAD_COND = (info['thread'] == 'pthread'
                      and info['lock'] == 'mutex+cond')
...
@unittest.skipIf(USING_PTHREAD_COND,
                 'POSIX condition variables cannot be interrupted')
-----------

I think that the test is more clear than:
-----------
@unittest.skipIf(info['name'] == 'pthread' and not
info['use_semaphores'],
                'POSIX mutexes cannot be interrupted')
-----------

(the message was wrong, the interrupt issue is on the condition, not on
the mutex)

> - you should not document unsupported platform names ("lwp", etc.); they
> are already disabled (#error)

Oh, I didn't realize that they were already unsupported as a compilation
error. Ok, fixed. I also removed "wince": I realized that thread_wince.h
is not used (see #11863).

The new patch (version 3) marks also PyThread_Info() as private (rename
it to _PyThread_Info).