[gtkada] Patch for gate with xalign alone property.

[Arnaud Charlet]

> Despite gate won't be supported any more, here is a patch.
> A gate error occurs when xalign property is not joined with yalign as
> attached example test2.glade.

Thanks. glib-glade.adb is no longer part of the GtkAda current sources, so
your patch cannot be applied (as you said, gate isn't supported anymore).

Arno