Revert "Fix T46284: Texture paint, wrong shading mode"

Should fix T46616 but will reintroduce T46284.
The second, original bug needs different handling

This reverts commit 904db487a7.

source/blender/editors/space_view3d/drawmesh.c

@@ -1114,7 +1114,8 @@ void draw_mesh_textured(Scene *scene, View3D *v3d, RegionView3D *rv3d,
 	/* if not cycles, or preview-modifiers, or drawing matcaps */
 	if ((draw_flags & DRAW_MODIFIERS_PREVIEW) ||
 	    (v3d->flag2 & V3D_SHOW_SOLID_MATCAP) ||
-	    (BKE_scene_use_new_shading_nodes(scene) == false))
+	    (BKE_scene_use_new_shading_nodes(scene) == false) ||
+	    ((ob->mode & OB_MODE_TEXTURE_PAINT) && ELEM(v3d->drawtype, OB_TEXTURE, OB_SOLID)))
 	{
 		draw_mesh_textured_old(scene, v3d, rv3d, ob, dm, draw_flags);
 		return;