[docs] Fix documentation build warnings
[docs] Fix documentation build warnings

Fix issues when using GI annotations so the xslt does a
fallback if the local links do not exist.

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=604876

djdeath/gdk-pixbuf,YueLinHo/MB3Gdk-pixbuf,djdeath/gdk-pixbuf,YueLinHo/MB3Gdk-pixbuf,GNOME/gdk-pixbuf,Distrotech/gdk-pixbuf,GNOME/gdk-pixbuf,djdeath/gdk-pixbuf,Distrotech/gdk-pixbuf,Distrotech/gdk-pixbuf,GNOME/gdk-pixbuf,djdeath/gdk-pixbuf,YueLinHo/MB3Gdk-pixbuf,YueLinHo/MB3Gdk-pixbuf,Distrotech/gdk-pixbuf,YueLinHo/MB3Gdk-pixbuf,GNOME/gdk-pixbuf,Distrotech/gdk-pixbuf