Fix Snake Hook rake on rotated objects

It was missing this local space conversion before calculating the rake
angle.

Reviewed By: jbakker

Differential Revision: https://developer.blender.org/D7008

source/blender/editors/sculpt_paint/sculpt.c

@@ -6767,6 +6767,9 @@ static void sculpt_update_brush_delta(UnifiedPaintSettings *ups, Object *ob, Bru
     /* Handle 'rake' */
     cache->is_rake_rotation_valid = false;
 
+    invert_m4_m4(imat, ob->obmat);
+    mul_mat3_m4_v3(imat, grab_location);
+
     if (cache->first_time) {
       copy_v3_v3(cache->rake_data.follow_co, grab_location);
     }