canvas-container: Remove unused signal

To be honest I don't know when it was used and where, but it's unused
now.

Fixes: https://gitlab.gnome.org/GNOME/nautilus/issues/801

src/nautilus-canvas-container.c

@@ -190,7 +190,6 @@ enum
     BAND_SELECT_STARTED,
     BAND_SELECT_ENDED,
     BUTTON_PRESS,
-    CAN_ACCEPT_ITEM,
     CONTEXT_CLICK_BACKGROUND,
     CONTEXT_CLICK_SELECTION,
     MIDDLE_CLICK,
@@ -3961,17 +3960,6 @@ nautilus_canvas_container_class_init (NautilusCanvasContainerClass *class)
                         NULL, NULL,
                         g_cclosure_marshal_generic,
                         G_TYPE_STRING, 0);
-    signals[CAN_ACCEPT_ITEM]
-        = g_signal_new ("can-accept-item",
-                        G_TYPE_FROM_CLASS (class),
-                        G_SIGNAL_RUN_LAST,
-                        G_STRUCT_OFFSET (NautilusCanvasContainerClass,
-                                         can_accept_item),
-                        NULL, NULL,
-                        g_cclosure_marshal_generic,
-                        G_TYPE_INT, 2,
-                        G_TYPE_POINTER,
-                        G_TYPE_STRING);
     signals[BAND_SELECT_STARTED]
         = g_signal_new ("band-select-started",
                         G_TYPE_FROM_CLASS (class),

src/nautilus-canvas-container.h

@@ -155,9 +155,6 @@ typedef struct {
 	 * These must be implemented => These are signals !
 	 * The default "do nothing" is not good enough.
 	 */
-	gboolean     (* can_accept_item)	  (NautilusCanvasContainer *container,
-						   NautilusCanvasIconData *target, 
-						   const char *item_uri);
 	gboolean     (* get_stored_icon_position) (NautilusCanvasContainer *container,
 						     NautilusCanvasIconData *data,
 						     NautilusCanvasPosition *position);