Remove unused variable in zip_hash_ancestors.
Under gcc 5.4.0, this generates unused variable warnings, which in combination
with -Werror causes a compile error.
There used to be C# bindings in this directory, but they have been
unmaintained for many years.
Instead, there is a more modern PhysicsFS wrapper for .NET available.
You can find it at https://github.com/frabert/SharpPhysFS
Thanks to Francesco Bertolaccini for his efforts on that project!
--ryan.