New review comment by ericonr on void-packages repository

https://github.com/void-linux/void-packages/pull/29972#discussion_r607071154

Comment:
Ok, these are *new* files. At least they don't seem to exist in the current version of the package.

In that case, it should be made a build option and `build_options_default="gir"` should only be set for the native build. This way, it's clear that the cross builds are lacking introspection support.