Fix clicking into texpaint slots not changing active image in blender

internal when using nodes.

Using nodes in blender internal is not well supported, but there's no
harm in allowing this and it will help manu do his texturing better :)

source/blender/makesrna/intern/rna_material.c

@@ -181,7 +181,7 @@ static void rna_Material_active_paint_texture_index_update(Main *bmain, Scene *s
 	bScreen *sc;
 	Material *ma = ptr->id.data;
 
-	if (ma->use_nodes && ma->nodetree && BKE_scene_use_new_shading_nodes(scene)) {
+	if (ma->use_nodes && ma->nodetree) {
 		struct bNode *node;
 		int index = 0;
 		for (node = ma->nodetree->nodes.first; node; node = node->next) {