Solve #1118868 and make a new release for 4.0.2-5

A happy new year! @kenhys

I think you already know that the packaging policy for gobject-introspection has been changes. I've received #1118868 a few months ago. Let me solve the issue in this merge request, including the other issues related to Standards-Version 4.7.3.

I'd like you to apply the changes, and make a new release of libhinawa debian package (v4.0.2-5). When finding any problems to generate new packages, I'd like to figure them out, since the packages for sister projects (libhinoko and libhitaki) include the same issues.

Cheers!