New review comment by paper42 on void-packages repository

https://github.com/void-linux/void-packages/pull/36324#discussion_r834791661

Comment:
```suggestion
hostmakedepends="glib-devel pkg-config $(vopt_if gtk_doc gi-docgen) $(vopt_if gir vala-devel)"
```
or is there a reason why you also added gtk-doc?