Remove 'libzip' dependency

It is not actually needed.

Signed-off-by: Jussi Virtanen <jussi.k.virtanen@gmail.com>
Merge pull request #30 from jvirtanen/cleanups/libzip

Remove 'libzip' dependency
Remove 'libzip' dependency from documentation

The 'libzip' dependency has already been removed. Update the
documentation accordingly.

Signed-off-by: Jussi Virtanen <jussi.k.virtanen@gmail.com>
Update GNU Classpath in build instructions

Signed-off-by: Pekka Enberg <penberg@kernel.org>
Merge pull request #32 from jvirtanen/cleanups/libzip-documentation

Remove 'libzip' dependency from documentation