MWL#17: Table elimination

- When collecting Item_subselect::refers_to, put references to the correct
  subselect entry.

sql/sql_lex.cc

@@ -1780,6 +1780,7 @@ void st_select_lex_unit::exclude_tree()
 
 void st_select_lex::mark_as_dependent(st_select_lex *last, Item *dependency)
 {
+  SELECT_LEX *next_to_last;
   /*
     Mark all selects from resolved to 1 before select where was
     found table as depended (of select where was found table)
@@ -1787,6 +1788,7 @@ void st_select_lex::mark_as_dependent(st_select_lex *last, Item *dependency)
   for (SELECT_LEX *s= this;
        s && s != last;
        s= s->outer_select())
+  {
     if (!(s->uncacheable & UNCACHEABLE_DEPENDENT))
     {
       // Select is dependent of outer select
@@ -1802,10 +1804,12 @@ void st_select_lex::mark_as_dependent(st_select_lex *last, Item *dependency)
           sl->uncacheable|= UNCACHEABLE_UNITED;
       }
     }
+    next_to_last= s;
+  }
   is_correlated= TRUE;
   this->master_unit()->item->is_correlated= TRUE;
   if (dependency)
-    this->master_unit()->item->refers_to.push_back(dependency);
+    next_to_last->master_unit()->item->refers_to.push_back(dependency);
 }
 
 bool st_select_lex_node::set_braces(bool value)      { return 1; }