Fixed (non crtitial) memory segment overrun

This was discovered as part of adding a protected memory area between
each area allocated by multi_alloc().

The patch that adds the protection will be pushed in 10.5.
This patch adds fixes that are unique for 10.10

sql/sql_select.cc

@@ -5312,7 +5312,7 @@ make_join_statistics(JOIN *join, List<TABLE_LIST> &tables_list,
   /* Initialize POSITION objects */
   for (i=0 ; i <= table_count ; i++)
     (void) new ((char*) (join->positions + i)) POSITION;
-  for (i=0 ; i <= sort_space ; i++)
+  for (i=0 ; i < sort_space ; i++)
     (void) new ((char*) (join->sort_positions + i)) POSITION;
 
   join->best_ref= stat_vector;