[gtkada] Cannot compile misc_pixbuf.c in Gtk-Ada 1.2.8

[Arnaud Charlet]

Frank,

we've tested GtkAda with gdk-pixbuf 0.6, and apparently gdk-pixbuf 0.8
has an incompatible API that breaks the build.

I would suggest either trying to find a C knowledgeable people that have
gdk-pixbuf 0.8 installed, or revert to gdk-pixbuf 0.6.

Arno