Issue 1089358.  Adds the siginterrupt() function, that is just a
wrapper around the system call with the same name.  Also added
test cases, doc changes and NEWS entry. Thanks Jason and Ralf
Schmitt.
diff --git a/Doc/library/signal.rst b/Doc/library/signal.rst
index afb3166..7fe7ec1 100644
--- a/Doc/library/signal.rst
+++ b/Doc/library/signal.rst
@@ -124,6 +124,21 @@
    exception to be raised.
 
 
+
+.. function:: siginterrupt(signalnum, flag)
+
+   Change system call restart behaviour: if *flag* is :const:`False`, system calls
+   will be restarted when interrupted by signal *signalnum*, else system calls will
+   be interrupted. Returns nothing. Availability: Unix, Mac (see the man page
+   :manpage:`siginterrupt(3)` for further information).
+   
+   Note that installing a signal handler with :func:`signal` will reset the restart
+   behaviour to interruptible by implicitly calling siginterrupt with a true *flag*
+   value for the given signal.
+
+   .. versionadded:: 2.6
+
+
 .. function:: signal(signalnum, handler)
 
    Set the handler for signal *signalnum* to the function *handler*.  *handler* can