Add std_auto_ptr.i defining typemaps for returning std::auto_ptr<>.

First of all sorry for accidentally pushing this in this repo instead of my own.

Second, this seems to work for me, i.e. the test suite passes for C#, Java, Python and Ruby (which I used as an example of a language for which these typemaps are not implemented), but I do have a couple of questions:

1. Trivial one: do we need the "li_" prefix? I don't know what is it for but used it for consistency with the existing files.
2. I'm not sure if the change in `Examples/test-suite/common.mk` is needed, I don't really understand what's going on there.
3. Should we have `Lib/std_auto_ptr.i` used for the other languages too, maybe just giving an `#error` for them? Currently some parts are duplicated among all three `std_auto_ptr.i` versions which is not ideal but, again, I did it for consistency with the existing files.