Proper forward declaration for Lua bindings (amend 2afef6e4bd)

libs/ardour/luabindings.cc

@@ -177,6 +177,7 @@ CLASSINFO(TimeAxisViewItem);
 CLASSINFO(TimeSelection);
 CLASSINFO(TrackSelection);
 CLASSINFO(TrackViewList);
+CLASSINFO(UIConfiguration);
 
 
 /* this needs to match gtk2_ardour/luasignal.h */
@@ -315,8 +316,6 @@ CLASSKEYS(LuaDialog::Message);
 CLASSKEYS(LuaDialog::Dialog);
 CLASSKEYS(LuaDialog::ProgressWindow);
 
-CLASSKEYS(UIConfiguration);
-
 #endif // end windows special case
 
 /* Some notes on Lua bindings for libardour and friends