We can do better with the SBValue.linked_list_iter() API by supplying a default

end of list test function as __eol_test__.

The simple example can be reduced to:

    for t in task_head.linked_list_iter('next'):
        print t

Modify the test program to exercise the API for both cases: supplying or not
supplying an end of list test function.

llvm-svn: 136144