eventcontroller: Move declaration

This is in preparation for exposing APIs in gtkwidget.c

gtk/gtkeventcontroller.h

@@ -24,7 +24,6 @@
 #error "Only <gtk/gtk.h> can be included directly."
 #endif
 
-typedef struct _GtkEventController GtkEventController;
 typedef struct _GtkEventControllerClass GtkEventControllerClass;
 
 #include <gdk/gdk.h>

gtk/gtktypes.h

@@ -36,6 +36,7 @@ G_BEGIN_DECLS
 typedef struct _GtkAdjustment          GtkAdjustment;
 typedef struct _GtkBuilder             GtkBuilder;
 typedef struct _GtkClipboard	       GtkClipboard;
+typedef struct _GtkEventController     GtkEventController;
 typedef struct _GtkRequisition	       GtkRequisition;
 typedef struct _GtkSelectionData       GtkSelectionData;
 typedef struct _GtkSettings            GtkSettings;