doc: Fix gtk-doc warning
doc: Fix gtk-doc warning

gdk-pixbuf.c:663: Warning: GdkPixbuf: GObject-Introspection specific
GTK-Doc tag "Rename to" has been deprecated, please use annotations on
the identifier instead.

GNOME/gdk-pixbuf,Distrotech/gdk-pixbuf,Distrotech/gdk-pixbuf,GNOME/gdk-pixbuf,GNOME/gdk-pixbuf,Distrotech/gdk-pixbuf,Distrotech/gdk-pixbuf,Distrotech/gdk-pixbuf,GNOME/gdk-pixbuf