Update documentation for last endpoint to mention inaddr_any and add a test for…

Update documentation for last endpoint to mention inaddr_any and add a test for IPC last endpoint checking

doc/zmq_getsockopt.txt

@@ -395,7 +395,8 @@ ZMQ_LAST_ENDPOINT: Retrieve the last endpoint set
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 The 'ZMQ_LAST_ENDPOINT' option shall retrieve the last endpoint bound for 
 TCP and IPC transports. The returned value will be a string in the form of
-a ZMQ DSN. 
+a ZMQ DSN. Note that if the TCP host is INADDR_ANY, indicated by a *, then
+the returned address will be 0.0.0.0 (for IPv4).
 
 [horizontal]
 Option value type:: character string

tests/test_last_endpoint.cpp

@@ -47,6 +47,13 @@ int main (int argc, char *argv [])
     rc = zmq_getsockopt (sb, ZMQ_LAST_ENDPOINT, test, &siz);
     assert (rc == 0 && strcmp (test, "tcp://127.0.0.1:54321") == 0);
 
+    rc = zmq_bind (sb, "ipc:///tmp/testep");
+    assert (rc == 0);
+
+    siz = 255;
+    rc = zmq_getsockopt (sb, ZMQ_LAST_ENDPOINT, test, &siz);
+    assert (rc == 0 && strcmp (test, "ipc:///tmp/testep") == 0);
+
     return 0 ;
 }