BUG: Avoid trying to graft missing examples directory
The examples directory was removed by #9391. Remove it from the MANIFEST too.
good point

out of curiosity does this have an effect when installing? (e.g. that it's not there) With some combinations of python (3.4.6) and setuptools (at least 32.1.0), graft traces with `FileNotFoundError` instead of a warning when a directory is missing. For example, see [devel/py-setuptools: egg_info fails under python 3.4.6 on nonexistent MANIFEST graft](https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=216953).

I wouldn't expect it to make any difference in other cases. The problem exists for setuptools < v34.0.1.

Adopting globs avoids the underlying trigger in 3.4.6: pypa/setuptools@9cb83c3711d737fa3bff56f55e4def8267bae83c thanks @neirbowj 