Create a default layout if none is given before inserting the core keyboard.

Index: keyboard_backend.py
===================================================================
--- system-config-keyboard-1.2.15/src/keyboard_backend.py	(revision 569)
+++ system-config-keyboard-1.2.15/src/keyboard_backend.py	(working copy)
@@ -44,6 +44,9 @@
                 keyboard.options.insert (xf86config.XF86Option("XkbModel", "pc101"))
                 keyboard.options.insert (xf86config.XF86Option("XkbLayout", "us"))
                 xconfig.input.insert (keyboard)
+                if len(xconfig.layout) == 0:
+                    xconfig.layout.insert(xf86config.XF86ConfLayout())
+
                 xconfig.layout[0].inputs.insert (xf86config.XF86ConfInputref ("Keyboard0", "CoreKeyboard"));
             
             found = 0