SF bug #1296

Patch proposition to fix SourceForge bug #1296. Includes simple test case.

## Test results

### unpatched

```
ptomulik@node00:~/projects$ cd ~/projects/swig/Examples/test-suite/python/
ptomulik@node00:~/projects/swig/Examples/test-suite/python$ make -s template_default_arg_virtual_destructor.cpptest
checking testcase template_default_arg_virtual_destructor under python
../../../Examples/test-suite/template_default_arg_virtual_destructor.i:20: Warning 521: Illegal destructor name B< A >::~B(). Ignored.
```

### patched
```
ptomulik@node00:~/projects$ cd ~/projects/swig/Examples/test-suite/python/
ptomulik@node00:~/projects/swig/Examples/test-suite/python$ make -s template_default_arg_virtual_destructor.cpptest
checking testcase template_default_arg_virtual_destructor under python
```