gtkdoc-scan make interfaces public

[Joël Krähemann <jkraehemann gmail com>]

Hi

I want to generate an API reference of my libraries. How to tell
gtkdoc-scan to make interfaces public? Currently interfaces don't have
cross references. I figured out how I can modify gtkdoc-scan to do
include it but isn't a satisfiable solution.

https://github.com/gsequencer/gsequencer

Bests,
Joël Krähemann