Fixed LP bug #754521.

The function test_quick_select by mistake did not update the value
of table->quick_condition_rows for index intersection scans though
the specification explicitly required to do so from any table access
plan once the plan provided a better upper bound for the number of
rows selected from the table. It resulted in a bogus, usually very
big number saved as the cost of the table access. This, in its turn,
in many cases forced the optimizer to make a bad choice of the
execution plan for join queries.

sql/opt_range.cc

@@ -3116,7 +3116,9 @@ int SQL_SELECT::test_quick_select(THD *thd, key_map keys_to_use,
                                                     best_read_time)))
         {
           best_trp= intersect_trp;
-          best_read_time= best_trp->read_cost;         
+          best_read_time= best_trp->read_cost; 
+          set_if_smaller(param.table->quick_condition_rows, 
+                         intersect_trp->records);
         }
       }