Enable more Drag&Drop actions when eom is drag source

Enable the link and ask actions allowing to create symlinks in Caja
or triggering a menu asking what to do. Also enable the move action,
which was not specifically enabled before but still worked anyway.

https://bugzilla.gnome.org/show_bug.cgi?id=667076

origin commit:
https://gitlab.gnome.org/GNOME/eog/commit/bcf7817

Author: fxri

src/eom-scroll-view.c

@@ -1800,7 +1800,8 @@ eom_scroll_view_init (EomScrollView *view)
 
 	gtk_drag_source_set (priv->display, GDK_BUTTON1_MASK,
 			     target_table, G_N_ELEMENTS (target_table),
-			     GDK_ACTION_COPY);
+			     GDK_ACTION_COPY | GDK_ACTION_MOVE |
+			     GDK_ACTION_LINK | GDK_ACTION_ASK);
 	g_signal_connect (G_OBJECT (priv->display), "drag-data-get",
 			  G_CALLBACK (view_on_drag_data_get_cb), view);
 	g_signal_connect (G_OBJECT (priv->display), "drag-begin",

src/eom-thumb-view.c

@@ -149,7 +149,10 @@ eom_thumb_view_constructed (GObject *object)
 
 	gtk_icon_view_enable_model_drag_source (GTK_ICON_VIEW (thumbview), 0,
 						NULL, 0,
-						GDK_ACTION_COPY);
+						GDK_ACTION_COPY |
+						GDK_ACTION_MOVE |
+						GDK_ACTION_LINK |
+						GDK_ACTION_ASK);
 	gtk_drag_source_add_uri_targets (GTK_WIDGET (thumbview));
 
 	g_signal_connect (G_OBJECT (thumbview), "drag-data-get",