Enable the tests and support of shared_ptr in them for C (which required
disabling a previously passing, because not doing anything, attributes
test which is currently broken for unrelated reasons).
Testcase has now been modified to mask the problem by providing the default parameter 'int' in:
%shared_ptr(Space::BaseDefault<short, int>)
If this is not done then d fails to convert to BaseDefault<short>&
This needs fixing in SWIG, but the problem is masked for now, so that the python
testcase works when run with the -O option.
