[gtkmm] Missing GTKMM_API for CellLayout

[Kjell Ahlstedt <kjellahl src gnome org>]

commit 10fb786f2d6704192df2cb5f23b41df4012c2f7b
Author: Mikhail Titov <mlt gmx us>
Date:   Wed May 6 19:19:58 2015 +0200

    Missing GTKMM_API for CellLayout
    
    This is used by Gtk::TreeViewColumn in gtkmm demo in particular. Bug #748720.

 gtk/src/celllayout.hg |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gtk/src/celllayout.hg b/gtk/src/celllayout.hg
index bfe2bf2..a65fbf2 100644
--- a/gtk/src/celllayout.hg
+++ b/gtk/src/celllayout.hg
@@ -42,7 +42,7 @@ class CellArea;
  * CellLayout is an interface to be implemented by all objects which want to provide a TreeView::Column-like 
API
  * for packing cells, setting attributes and data funcs.
  */
-class CellLayout : public Glib::Interface
+class GTKMM_API CellLayout : public Glib::Interface
 {
   _CLASS_INTERFACE(CellLayout, GtkCellLayout, GTK_CELL_LAYOUT, GtkCellLayoutIface)