gtk/: fully remove gtkalias hacks

https://bugzilla.gnome.org/show_bug.cgi?id=623845

gtk/gtktreemodelsort.c

@@ -47,7 +47,7 @@
 #include "gtkintl.h"
 #include "gtkprivate.h"
 #include "gtktreednd.h"
-#include "gtkalias.h"
+
 
 typedef struct _SortElt SortElt;
 typedef struct _SortLevel SortLevel;
@@ -2519,6 +2519,3 @@ gtk_tree_model_sort_iter_is_valid (GtkTreeModelSort *tree_model_sort,
   return gtk_tree_model_sort_iter_is_valid_helper (iter,
 						   tree_model_sort->root);
 }
-
-#define __GTK_TREE_MODEL_SORT_C__
-#include "gtkaliasdef.c"