gmmproc: Make h2def.py recognize some GDK_PIXBUF macros
gmmproc: Make h2def.py recognize some GDK_PIXBUF macros

gdk-pixbuf has added macros such as GDK_PIXBUF_DEPRECATED* and
GDK_PIXBUF_AVAILABLE* in the header files. h2def.py must recognize those
macros in order to successfully decode the function declarations.

GNOME/glibmm,GNOME/glibmm,GNOME/glibmm,GNOME/glibmm,GNOME/glibmm