LinGui: fix problem cause by change in behavior of libgtk

gtk_buildable_get_name and gtk_widget_get_name now return a string
describing the widget type if the name has not been set instead of
NULL as they used to.  This of coarse breaks everything that depends
on looking up valid widget names.


git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6131 b64f7644-9d1e-0410-96f1-a4d463321fa5