Issue #11223: Add threading._info() function providing informations about the
thread implementation.

Skip test_lock_acquire_interruption() and test_rlock_acquire_interruption() of
test_threadsignals if a thread lock is implemented using a POSIX mutex and a
POSIX condition variable. A POSIX condition variable cannot be interrupted by a
signal (e.g. on Linux, the futex system call is restarted).
diff --git a/Doc/whatsnew/3.3.rst b/Doc/whatsnew/3.3.rst
index 602b2b7..d3c9a97 100644
--- a/Doc/whatsnew/3.3.rst
+++ b/Doc/whatsnew/3.3.rst
@@ -112,6 +112,14 @@
 
 (Contributed by Giampaolo Rodolà in :issue:`9795`)
 
+threading
+---------
+
+* The :mod:`threading` module has a new :func:`~threading._info` function which
+  provides informations about the thread implementation.
+
+  (:issue:`11223`)
+
 Optimizations
 =============