WL3527: post-merge updates

sql_yacc.yy:
  WL3527: updated the diff to use correct parser words
table.cc:
  WL3527: exteneded the fix for bug #20604 to fit the new variables
sql_select.cc:
  WL3527: renamed used_keys to covering_keys

sql/sql_select.cc

@@ -654,7 +654,7 @@ void JOIN::remove_subq_pushed_predicates(Item **where)
 static void save_index_subquery_explain_info(JOIN_TAB *join_tab, Item* where)
 {
   join_tab->packed_info= TAB_INFO_HAVE_VALUE;
-  if (join_tab->table->used_keys.is_set(join_tab->ref.key))
+  if (join_tab->table->covering_keys.is_set(join_tab->ref.key))
     join_tab->packed_info |= TAB_INFO_USING_INDEX;
   if (where)
     join_tab->packed_info |= TAB_INFO_USING_WHERE;

sql/sql_yacc.yy

@@ -7548,7 +7548,7 @@ index_hint_clause:
          } 
        | FOR_SYM JOIN_SYM      { $$= INDEX_HINT_MASK_JOIN;  }
        | FOR_SYM ORDER_SYM BY  { $$= INDEX_HINT_MASK_ORDER; }
-       | FOR_SYM GROUP BY      { $$= INDEX_HINT_MASK_GROUP; }
+       | FOR_SYM GROUP_SYM BY  { $$= INDEX_HINT_MASK_GROUP; }
        ;
 
 index_hint_type:

sql/table.cc

@@ -4272,11 +4272,11 @@ bool st_table_list::process_index_hints(TABLE *table)
 
     /* apply USE INDEX */
     if (!index_join[INDEX_HINT_USE].is_clear_all() || have_empty_use_join)
-      table->keys_in_use_for_query= index_join[INDEX_HINT_USE];
+      table->keys_in_use_for_query.intersect(index_join[INDEX_HINT_USE]);
     if (!index_order[INDEX_HINT_USE].is_clear_all() || have_empty_use_order)
-      table->keys_in_use_for_order_by= index_order[INDEX_HINT_USE];
+      table->keys_in_use_for_order_by.intersect (index_order[INDEX_HINT_USE]);
     if (!index_group[INDEX_HINT_USE].is_clear_all() || have_empty_use_group)
-      table->keys_in_use_for_group_by= index_group[INDEX_HINT_USE];
+      table->keys_in_use_for_group_by.intersect (index_group[INDEX_HINT_USE]);
 
     /* apply IGNORE INDEX */
     table->keys_in_use_for_query.subtract (index_join[INDEX_HINT_IGNORE]);