ignore unused parameter 'buf' warning

[peter-urban]

I included <xtensor-python/xtensor_type_caster_base.hpp> into my code to let pybind11 automatically convert xtensor xarrays to numpy arrays.

However I get two "-wunused-parameter warnings" which seem to be straightforward to fix :-)

[peter-urban]

Not sure, but the appveyor fail seems to be unrelated to my pull request?

[tdegeus]

Thanks! You could also just remove the name buf from the argument. Is there any reason to keep it?

[peter-urban]

I don't understand the code well enough to propose such a change.

To me this looks like a dummy function (just just returns true) to implement a sort of interface (but I don't know which one). Removing the variable could thus break this interface.

That said: If you have a better understanding of the code-base and you say that we can remove the argument, it is of cause not problem for me to adapt the PR :-)

[tdegeus]

Tanks!