file chooser: give GSettings schema a path

The code is always instantiating this schema at a fixed location, so why
is it relocatable?

Add a path so that it shows up properly in dconf-editor, and from the
gsettings commandline tool.

https://bugzilla.gnome.org/show_bug.cgi?id=692163

gtk/gtkfilechooserdefault.c

@@ -6020,8 +6020,7 @@ settings_ensure (GtkFileChooserDefault *impl)
   if (impl->settings != NULL)
     return;
 
-  impl->settings = g_settings_new_with_path ("org.gtk.Settings.FileChooser",
-                                             "/org/gtk/settings/file-chooser/");
+  impl->settings = g_settings_new ("org.gtk.Settings.FileChooser");
   g_settings_delay (impl->settings);
 }
 

gtk/org.gtk.Settings.FileChooser.gschema.xml

@@ -33,7 +33,7 @@
     <value nick='descending' value='1'/>
   </enum>
 
-  <schema id='org.gtk.Settings.FileChooser'>
+  <schema id='org.gtk.Settings.FileChooser' path='/org/gtk/settings/file-chooser/'>
     <key name='last-folder-uri' type='s'>
       <default>""</default>
     </key>